CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Preferred Stock	Surplus	Retained earnings	Treasury Stock	Accumulated other comprehensive income (loss)
Beginning Balance at Dec. 31, 2016	$ 5,197,957	$ 1,040	$ 50,160	$ 4,255,022	$ 1,220,307	$ (8,286)	$ (320,286)
Net Income	92,945				92,945
Issuance of stock	1,807	1		1,806
Dividends declared:
Dividends, Common Stock, Cash	(25,615)				(25,615)
Dividends, Preferred Stock, Cash	(931)				(931)
Common stock purchases	(76,324)			4,518		(80,842)
Other comprehensive loss, net of tax	374						374
Ending Balance at Mar. 31, 2017	5,190,213	1,041	50,160	4,261,346	1,286,706	(89,128)	(319,912)
Beginning Balance at Dec. 31, 2017	5,103,905	1,042	50,160	4,298,503	1,194,994	(90,142)	(350,652)
Net Income	91,324				91,324
Issuance of stock	881	1		880
Dividends declared:
Dividends, Common Stock, Cash	(25,547)				(25,547)
Dividends, Preferred Stock, Cash	(931)				(931)
Common stock purchases	(1,328)					(1,328)
Common stock reissuance	722			(16)		738
Stock based compensation	6,134			1,569		4,565
Other comprehensive loss, net of tax	(112,186)						(112,186)
Ending Balance at Mar. 31, 2018	5,064,909	$ 1,043	$ 50,160	$ 4,300,936	1,261,775	$ (86,167)	$ (462,838)
Cumulative effect of accounting change	$ 1,935				$ 1,935