Summary of Significant Accounting Policies Adjustments to Quarterly Financial Information (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Income tax provision	$ 9,200	$ 989	$ 5,188	$ 9,350					$ 19,450	$ 43,555	$ 35,527
Net income	$ 31,196	$ 35,430	$ 25,007	$ 18,224	$ 8,618	$ 20,142	$ 18,836	$ 17,273	$ 109,857	$ 64,869	$ 58,940
Basic (USD per share)		$ 0.97	$ 0.69	$ 0.50					$ 3.01	$ 1.90	$ 1.79
Diluted (USD per share)	$ 0.80	$ 0.91	$ 0.65	$ 0.47	$ 0.23	$ 0.55	$ 0.52	$ 0.48	$ 2.82	$ 1.77	$ 1.66
Diluted weighted average shares outstanding (in shares)	38,975	39,062	38,738	39,071	37,864	36,349	36,097	35,895	38,961	36,552	35,401
Net cash provided by operating activities		$ 79,213	$ 19,520	$ 41,321					$ 191,859	$ 134,327	$ 142,839
Net cash (used) provided by financing activities		(90,095)	25	(16,911)					$ (138,075)	$ 91,052	$ (3,993)
Scenario, Previously Reported
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Income tax provision		14,155	11,323	10,495
Net income		$ 22,264	$ 18,872	$ 17,079
Basic (USD per share)		$ 0.61	$ 0.52	$ 0.47
Diluted (USD per share)		$ 0.58	$ 0.49	$ 0.44
Diluted weighted average shares outstanding (in shares)		38,506	38,196	38,557
Net cash provided by operating activities		$ 67,091	$ 13,877	$ 40,270
Net cash (used) provided by financing activities		$ (77,973)	$ 5,668	$ (15,860)