Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Net income to common shareholders	$ 149,296	$ 131,461	$ 175,722
Net income allocated to participating securities - basic and diluted	3,598	2,895	3,631
Net income allocated to common shareholders - basic and diluted	$ 145,698	$ 128,566	$ 172,091
Weighted-average common shares - basic	77,850,000	78,197,000	81,804,000
Dilutive potential common shares	99,000	110,000	230,000
Weighted-average common shares - diluted	77,949,000	78,307,000	82,034,000
Earnings per common share: Basic	$ 1.87	$ 1.64	$ 2.10
Earnings per common share: Diluted	$ 1.87	$ 1.64	$ 2.10
Weighted-average anti-dilutive potential common shares	572,512	798,623	621,327
Hancock [Member]
Net income to common shareholders	$ 149,296	$ 131,461	$ 175,722