Summary of Significant Accounting Policies - New Accounting Pronouncements Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended	12 Months Ended
		Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jan. 01, 2019	Jan. 01, 2018	Jan. 01, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Impact of adoption of new accounting standard						$ (1,636)	$ 1,851
Right-of-use assets, net		$ 0	$ 10,151	$ 0		6,600
Lease liabilities			9,088			9,100
Accumulated deficit		(961,689)	(914,791)	(961,689)
Increase to net income from continuing operations			$ 48,148	$ 51,569	$ 29,376
Basic net income (loss) per share (in USD per share)	[1]		$ 1.00	$ 0.94	$ 0.61
Diluted net income (loss) per share (in USD per share)	[1]		$ 0.98	$ 0.90	$ 0.57
Increase to cash provided by operating activities			$ 92,804	$ 105,548	$ 72,846
Decrease to cash used in financing activities			77,836	(74,804)	(68,562)
Revenue			717,945	560,456	509,557
Reduction to operating expenses			717,936	492,779	461,520
Cumulative effect on unaudited quarterly results			48,148	51,569	29,376
Adjustment to additional paid-in capital, stock-based compensation			16,300	13,253	64,344
Accounting Standards Update 2014-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenue				1,800
Accounting Standards Update 2016-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Share-based compensation, excess tax benefit					20,100
Increase to net income from continuing operations					$ 20,100
Basic net income (loss) per share (in USD per share)					$ 0.45
Diluted net income (loss) per share (in USD per share)					$ 0.43
Increase to cash provided by operating activities				16,000
Accumulated deficit
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Impact of adoption of new accounting standard						$ (1,636)	1,851
Adjustment to additional paid-in capital, stock-based compensation				0	$ 51,543
Accumulated deficit | Accounting Standards Update 2014-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Impact of adoption of new accounting standard							$ 1,800
Additional paid-in capital
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Adjustment to additional paid-in capital, stock-based compensation			$ 16,300	13,253	$ 12,801
Additional paid-in capital | Accounting Standards Update 2016-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Impact of adoption of new accounting standard								$ 51,500
Calculated under Revenue Guidance in Effect before Topic 606 | Accounting Standards Update 2014-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenue				$ 3,300
Restatement Adjustment | New Accounting Pronouncement, Effect of Early Adoption | Accounting Standards Update 2018-07
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Adjustment to additional paid-in capital, stock-based compensation		$ 300

[1] Net income per share for the year ended December 31, 2018 included the noncontrolling interest redemption impact discussed further in “Note 2—Summary of Significant Accounting Policies” and in “Note 17—Net Income Per Share.”