Employee Benefits and Share-Based Compensation - Stock Option Activity (Details) - 2009 Plan - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Number of Shares
Outstanding at beginning of period (in shares)			3,214
Granted (in shares)			409
Exercised (in shares)			(423)
Expired (in shares)			(3)
Forfeited (in shares)			(56)
Outstanding at end of period (in shares)	3,141		3,141		3,214
Exercisable at end of period (in shares)	1,382		1,382
Vested and expected to vest at end of period (in shares)	2,985		2,985
Weighted Average Exercise Price
Outstanding beginning balance (in dollars per share)			$ 26.06
Granted (in dollars per share)			37.21
Exercised (in dollars per share)			21.69
Expired (in dollars per share)			24.36
Forfeited (in dollars per share)			32.14
Outstanding ending balance (in dollars per share)	$ 27.99		27.99		$ 26.06
Exercisable at end of period (in dollars per share)	21.61		21.61
Vested and expected to vest at end of period (in dollars per share)	$ 27.66		$ 27.66
Weighted-average remaining years, outstanding			7 years 5 months 5 days		7 years 3 months 18 days
Weighted-average remaining years, exercisable at end of period			5 years 7 months 2 days
Weighted-average remaining years, vested and expected to vest at at end of period			7 years 4 months 2 days
Aggregate Intrinsic Value
Aggregate intrinsic value, outstanding at end of period	$ 47,445		$ 47,445		$ 26,331
Aggregate intrinsic value, exercisable at end of period	29,696		29,696
Aggregate intrinsic value, vested and expected to vest at end of period	$ 46,078		$ 46,078
Employee Stock Option
Aggregate Intrinsic Value
Weighted-average fair value (in dollars per share)	$ 11.31	$ 9.03	$ 10.92	$ 8.59
Intrinsic value of options exercised	$ 4,900	$ 2,200	$ 7,800	$ 2,900
Unrecognized compensation cost of unvested stock options	$ 14,300		$ 14,300
Weighted average period of compensation cost not yet recognized (in years)			2 years 10 months 24 days