into an unsecured revolving credit facility (the “Credit Agreement”) with a syndicate of lenders that provides us with a borrowing capacity of up to $2.0 billion. We had no borrowings outstanding under the Credit Agreement as of December 31, 2014. See Item 8 of Part II, “Financial Statements and Supplementary Data—Note 6—Long-Term Debt” for additional information. 

In 2014 , 2013 , and 2012 we recorded net tax provisions of $167 million , $161 million , and $428 million . Except as required under U.S. tax laws, we do not provide for U.S. taxes on our undistributed earnings of foreign subsidiaries that have not been previously taxed since we intend to invest such undistributed earnings indefinitely outside of the U.S. If our intent changes or if these funds are needed for our U.S. operations, we would be required to accrue or pay U.S. taxes on some or all of these undistributed earnings and our effective tax rate would be adversely affected. As of December 31, 2014 , cash, cash equivalents, and marketable securities held by foreign subsidiaries were $4.6 billion, which included undistributed earnings of foreign subsidiaries indefinitely invested outside of the U.S. of $2.5 billion . We have tax benefits relating to excess stock-based compensation deductions and accelerated depreciation deductions that are being utilized to reduce our U.S. taxable income. In December 2014, U.S. legislation was enacted providing a one year extension of accelerated depreciation deductions on qualifying property through 2014. Cash taxes paid (net of refunds) were $177 million , $169 million , and $112 million for 2014 , 2013 , and 2012 . As of December 31, 2014 , our federal net operating loss carryforward was approximately $1.9 billion and we had approximately $443 million of federal tax credits potentially available to offset future tax liabilities. Our federal tax credits are primarily related to the U.S. federal research and development credit, which expired in 2014. As we utilize our federal net operating losses and tax credits, we expect cash paid for taxes to significantly increase. We endeavor to manage our global taxes on a cash basis, rather than on a financial reporting basis. 

Our liquidity is also affected by restricted cash balances that are pledged as collateral for standby and trade letters of credit, guarantees, debt, and real estate leases. To the extent we process payments for third-party sellers or offer certain types of stored value to our customers, some jurisdictions may restrict our use of those funds. These restrictions would result in the reclassification of a portion of our cash and cash equivalents from “Cash and cash equivalents” to “Accounts receivable, net and other” on our consolidated balance sheets. As of December 31, 2014 and 2013 , restricted cash, cash equivalents, and marketable securities were $450 million and $301 million . See Item 8 of Part II, “Financial Statements and Supplementary Data—Note 8—Commitments and Contingencies” for additional discussion of our principal contractual commitments, as well as our pledged assets. Purchase obligations and open purchase orders, consisting of inventory and significant