Commitments and Contingencies - Schedule of Future Minimum Payments for Obligations and Rent Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Sublease Income
Rent expense, net of sublease income	$ 4,800	$ 7,400	$ 6,300
Office Lease Obligations
Lease Commitments
2018	9,503
2019	10,438
2020	9,429
2021	7,877
2022	8,116
Thereafter	31,733
Total minimum lease payments	77,096
Sublease Income
2018	(2,116)
2019	(1,970)
2020	(1,186)
2021	0
2022	0
Thereafter	0
Total minimum lease payments	$ (5,272)