Stock Based Compensation - Stock Based Compensation Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Number of Options, Granted (in shares)	0	0	0	0
Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Number of Options, Outstanding, at December 31, 2016 (in shares)			811,902
Number of Options, Granted (in shares)			0
Number of Options, Exercised (in shares)			(349,880)
Number of Options, Forfeited (in shares)			0
Number of Options, Outstanding, at September 30, 2017 (in shares)	462,022		462,022		811,902
Number of Options, Vested and exercisable at September 30, 2017 (in shares)	462,022		462,022
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Weighted-Average Exercise Price, Outstanding, at December 31, 2016 (in dollars per share)			$ 16.31
Weighted-Average Exercise Price, Granted (in dollars per share)			0.00
Weighted-Average Exercise Price, Exercised (in dollars per share)			12.22
Weighted-Average Exercise Price, Forfeited (in dollars per share)			0.00
Weighted-Average Exercise Price, Outstanding, at September 30, 2017 (in dollars per share)	$ 19.40		19.40		$ 16.31
Weighted Average Exercise Price, Vested and exercisable at September 30, 2017 (in dollars per share)	$ 19.40		$ 19.40
Aggregate Intrinsic Value, Outstanding	$ 17,980		$ 17,980		$ 27,718
Weighted-Average Remaining Contractual Life			2 years 11 months 19 days		2 years 11 months 15 days
Aggregate Intrinsic Value, Vested and exercisable at September 30, 2017	$ 17,980		$ 17,980
Weighted-Average Remaining Contractual Life, Vested and exercisable at September 30, 2017			2 years 11 months 19 days