Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Earnings per share — Basic:
Earnings from continuing operations	$ 74,042	$ 85,917	$ 130,227	$ 139,243
Less: Earnings allocated to unvested stock	(235)	(246)	(398)	(393)
Earnings from continuing operations available to common shareholders — Basic	$ 73,807	$ 85,671	$ 129,829	$ 138,850
Weighted average common shares outstanding - Basic (shares)	53,057	52,827	53,067	52,712
Earnings from continuing operations per common share — Basic (in dollars per share)	$ 1.39	$ 1.62	$ 2.45	$ 2.63
Earnings per share — Diluted:
Earnings from continuing operations	$ 74,042	$ 85,917	$ 130,227	$ 139,243
Less: Earnings allocated to unvested stock	(234)	(244)	(397)	(390)
Earnings from continuing operations available to common shareholders — Diluted	$ 73,808	$ 85,673	$ 129,830	$ 138,853
Weighted average common shares outstanding - Basic (shares)	53,057	52,827	53,067	52,712
Effect of dilutive equity awards (shares)	320	468	303	492
Weighted average common shares outstanding — Diluted (shares)	53,377	53,295	53,370	53,204
Earnings from continuing operations per common share — Diluted (in dollars per share)	$ 1.38	$ 1.61	$ 2.43	$ 2.61
Anti-dilutive equity awards not included above (shares)	669	363	928	273