Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Earnings per share — Basic:
Earnings from continuing operations	$ 51,343	$ 74,042	$ 89,622	$ 130,227
Less: Earnings allocated to unvested stock	(186)	(235)	(317)	(398)
Earnings from continuing operations available to common shareholders — Basic	$ 51,157	$ 73,807	$ 89,305	$ 129,829
Weighted average common shares outstanding - Basic (in shares)	52,663	53,057	52,804	53,067
Earnings from continuing operations per common share — Basic (in dollars per share)	$ 0.97	$ 1.39	$ 1.69	$ 2.45
Earnings per share — Diluted:
Earnings from continuing operations	$ 51,343	$ 74,042	$ 89,622	$ 130,227
Less: Earnings allocated to unvested stock	(186)	(234)	(317)	(397)
Earnings from continuing operations available to common shareholders — Diluted	$ 51,157	$ 73,808	$ 89,305	$ 129,830
Weighted average common shares outstanding - Basic (in shares)	52,663	53,057	52,804	53,067
Effect of dilutive equity awards (in shares)	244	320	348	303
Weighted average common shares outstanding — Diluted (shares)	52,907	53,377	53,152	53,370
Earnings from continuing operations per common share — Diluted (in dollars per share)	$ 0.97	$ 1.38	$ 1.68	$ 2.43
Anti-dilutive equity awards not included above (in shares)	1,231	699	911	928