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, 2017		$ 5,103,905	$ 1,042	$ 50,160	$ 4,298,503	$ 1,194,994	$ (90,142)	$ (350,652)
Increase Decrease In Stockholders Equity [Roll Forward]
Net Income		91,324				91,324
Issuance of stock		881	1		880
Dividends declared:
Common stock	[1]	(25,547)				(25,547)
Preferred stock		(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)
Increase Decrease In Stockholders Equity [Roll Forward]
Cumulative effect of accounting change		1,935				1,935
Beginning Balance at Dec. 31, 2018		5,435,057	1,043	50,160	4,365,606	1,651,731	(205,509)	(427,974)
Increase Decrease In Stockholders Equity [Roll Forward]
Net Income		167,925				167,925
Issuance of stock		793			793
Dividends declared:
Common stock	[1]	(28,986)				(28,986)
Preferred stock		(931)				(931)
Common stock purchases	[2]	(253,119)			(52,670)		(200,449)
Common stock reissuance		2,183			178		2,005
Stock based compensation		8,238			(867)		9,105
Other comprehensive loss, net of tax		103,995						103,995
Ending Balance at Mar. 31, 2019		5,440,060	$ 1,043	$ 50,160	$ 4,313,040	1,794,644	$ (394,848)	$ (323,979)
Increase Decrease In Stockholders Equity [Roll Forward]
Cumulative effect of accounting change		$ 4,905				$ 4,905

[1] Dividends declared per common share during the quarter ended March 31, 2019 - $0.30 (2018 - $0.25).

[2] On February 28, 2019, the Corporation entered into a $250 million accelerated share repurchase transaction with respect to its common stock, which was accounted for as a treasury stock transaction. Refer to Note 18 for additional information.