Consolidated Statements of Shareholders' Equity - USD ($) $ in Thousands	Total	Preferred Stock	Common Stock	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)
Beginning balance (in shares) at Dec. 31, 2018		13,750	54,796,231
Beginning balance at Dec. 31, 2018	$ 4,056,277	$ 132,097	$ 54,796	$ 2,869,416	$ 1,042,718	$ (42,750)
Increase (Decrease) in Shareholders' Equity
Net income	100,131				100,131
Other comprehensive income (loss)	39,450					39,450
Cash dividends declared	(23,457)				(23,457)
Preferred stock dividends	(3,598)				(3,598)
Common stock issued under incentive plans, net of shares surrendered in payment (in shares)			142,954
Common stock issued under incentive plans, net of shares surrendered in payment	(4,445)		$ 143	(4,588)
Common stock repurchases (in shares)			(387,921)
Common stock repurchases	(29,946)		$ (388)	(29,558)
Share-based compensation expense	5,572			5,572
Ending balance (in shares) at Mar. 31, 2019		13,750	54,551,264
Ending balance at Mar. 31, 2019	4,141,831	$ 132,097	$ 54,551	2,840,842	1,117,641	(3,300)
Beginning balance (in shares) at Dec. 31, 2019		23,750	52,419,519
Beginning balance at Dec. 31, 2019	4,336,734	$ 228,485	$ 52,420	2,688,263	1,322,805	44,761
Increase (Decrease) in Shareholders' Equity
Net income	36,425				36,425
Other comprehensive income (loss)	66,423					66,423
Cash dividends declared	(24,729)				(24,729)
Preferred stock dividends	(3,598)				(3,598)
Common stock issued under incentive plans, net of shares surrendered in payment (in shares)			198,768
Common stock issued under incentive plans, net of shares surrendered in payment	(3,575)		$ 198	(3,773)
Share-based compensation expense	7,032			7,032
Ending balance (in shares) at Mar. 31, 2020		23,750	52,618,287
Ending balance at Mar. 31, 2020	$ 4,347,107	$ 228,485	$ 52,618	$ 2,691,522	$ 1,263,298	$ 111,184