Income Taxes - Reconciliation of Income Tax Expense (Benefit) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Expense (Benefit), Continuing Operations, Income Tax Reconciliation [Abstract]
Tax at federal statutory rate									$ 36,400	$ 20,031	$ 2,786
State, net of federal benefit									1,635	622	175
Contingent liabilities									948	903	1,225
Stock-based compensation									(8,131)	(4,019)	263
Research and development credits									(2,758)	(2,821)	(1,525)
Change in uncertain tax positions									858	1,308	1,423
Rate change for changes in federal or state law									178	32,429	25
Change in valuation allowance									(4,225)	(4,169)	6,283
Expired NOLs and credits									3,054	0	0
Change in derivatives									615	0	0
Other									1,435	391	(328)
Income tax expense from continuing operations	$ 37,674	$ 3,645	$ 2,242	$ 1,114	$ (14,307)	$ 11,864	$ 22,419	$ 10,033	$ 30,009	$ 44,675	$ 10,327