Long-Term Debt	9 Months Ended
Sep. 30, 2017
Debt Disclosure [Abstract]
Long-Term Debt	Long-Term Debt 2015 Credit Agreement In December 2015, the Company entered into a second amended and restated credit agreement (the “Senior Facility”) that allowed the Company to borrow up to $250.0 million, including up to $50.0 million for the issuance of letters of credit and up to $25.0 million for swing line loans. As of September 30, 2017, there were no outstanding borrowings under the Senior Facility. As of September 30, 2017, the Company had outstanding letters of credit totaling $38.3 million, issued to cover various security deposits on its facility leases. On May 3, 2017, the Company entered into a first amendment to the Senior Facility (the “First Amendment”), pursuant to which the aggregate amount the Company can borrow under the Senior Facility was reduced from $250.0 million to $100.0 million, with up to $50.0 million available for the issuance of letters of credit and up to $25.0 million available for swing line loans. In addition, pursuant to the First Amendment, the applicable margin in respect of the interest rates under the Senior Facility were amended to be based on the Company’s level of liquidity (defined as the sum of the Company’s aggregate cash holdings and the amount available under its revolving commitments) and range from, with respect to Alternate Base Rate loans, 0.5% to 1.0%, and, with respect to LIBOR loans, 1.5% to 2.0%. Among other changes, the First Amendment also removed the fixed charge coverage ratio covenant and the consolidated leverage ratio covenant, and added a general liquidity covenant requiring the Company to maintain liquidity of at least $200.0 million in unrestricted cash, of which $100.0 million in cash or cash equivalents must be held in accounts subject to control agreements with, and maintained by, Silicon Valley Bank or its affiliates. The Company was in compliance with the financial covenants under the Senior Facility as of September 30, 2017. Letters of Credit As of September 30, 2017 and December 31, 2016, the Company had outstanding letters of credit totaling $38.3 million and $38.0 million, respectively, issued to cover various security deposits on the Company’s facility leases.

Long-Term Debt

2015 Credit Agreement

In December 2015, the Company entered into a second amended and restated credit agreement (the “Senior Facility”) that allowed the Company to borrow up to $250.0 million, including up to $50.0 million for the issuance of letters of credit and up to $25.0 million for swing line loans. As of September 30, 2017, there were no outstanding borrowings under the Senior Facility. As of September 30, 2017, the Company had outstanding letters of credit totaling $38.3 million, issued to cover various security deposits on its facility leases.

On May 3, 2017, the Company entered into a first amendment to the Senior Facility (the “First Amendment”), pursuant to which the aggregate amount the Company can borrow under the Senior Facility was reduced from $250.0 million to $100.0 million, with up to $50.0 million available for the issuance of letters of credit and up to $25.0 million available for swing line loans. In addition, pursuant to the First Amendment, the applicable margin in respect of the interest rates under the Senior Facility were amended to be based on the Company’s level of liquidity (defined as the sum of the Company’s aggregate cash holdings and the amount available under its revolving commitments) and range from, with respect to Alternate Base Rate loans, 0.5% to 1.0%, and, with respect to LIBOR loans, 1.5% to 2.0%. Among other changes, the First Amendment also removed the fixed charge coverage ratio covenant and the consolidated leverage ratio covenant, and added a general liquidity covenant requiring the Company to maintain liquidity of at least $200.0 million in unrestricted cash, of which $100.0 million in cash or cash equivalents must be held in accounts subject to control agreements with, and maintained by, Silicon Valley Bank or its affiliates. The Company was in compliance with the financial covenants under the Senior Facility as of September 30, 2017.

Letters of Credit

As of September 30, 2017 and December 31, 2016, the Company had outstanding letters of credit totaling $38.3 million and $38.0 million, respectively, issued to cover various security deposits on the Company’s facility leases.