New Accounting Standards (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2016	Dec. 31, 2015	Sep. 30, 2015	Dec. 31, 2014
Cumulative Effect Adjustments to Condensed Consolidated Statement of Financial Position [Abstract]
Deferred tax assets	$ 32,156	$ 32,156	$ 39,635
Total assets	2,538,319	2,538,319	2,409,066
Common stock	323,303	323,303	339,462
Accumulated deficit	(69,386)	(69,386)	(82,334)
Total Shareholders' Equity	250,902	250,902	251,092	$ 252,980	$ 250,371
Total Liabilities and Shareholders' Equity	2,538,319	2,538,319	2,409,066
Income tax expense (benefit)	0	(300)
ASU 2016-09 [Member]
Cumulative Effect Adjustments to Condensed Consolidated Statement of Financial Position [Abstract]
Deferred tax assets			40,882
Total assets			2,410,313
Common stock			339,524
Accumulated deficit			(81,149)
Total Shareholders' Equity			252,339
Total Liabilities and Shareholders' Equity			2,410,313
Unrealized excess benefits on share based compensation		1,230
Forfeiture provision		60
Impact to equity after consideration of deferred taxes		20
Income tax expense (benefit)	$ 0	$ (300)
ASU 2016-09 [Member] | Originally Presented [Member]
Cumulative Effect Adjustments to Condensed Consolidated Statement of Financial Position [Abstract]
Deferred tax assets			39,635
Total assets			2,409,066
Common stock			339,462
Accumulated deficit			(82,334)
Total Shareholders' Equity			251,092
Total Liabilities and Shareholders' Equity			2,409,066
ASU 2016-09 [Member] | Cumulative Retrospective Adjustments [Member]
Cumulative Effect Adjustments to Condensed Consolidated Statement of Financial Position [Abstract]
Deferred tax assets			1,247
Total assets			1,247
Common stock			62
Accumulated deficit			1,185
Total Shareholders' Equity			1,247
Total Liabilities and Shareholders' Equity			$ 1,247