Parent Company Cash Flow Statement (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2021	Dec. 31, 2020		Dec. 31, 2019
Condensed Financial Statements, Captions [Line Items]
Net income		$ 120,992	$ 121,167		$ 165,175
Adjustments to reconcile net income to net cash provided by operating activities
Deferred income tax expense		3,090	(17,506)		10,594
Change in other liabilities		(58,503)	76,140		19,283
Net cash provided by operating activities		190,220	64,636		216,522
Cash flows provided by (used) in investing activities
Net cash used in investing activities		(63,136)	(488,211)		20,160
Cash flows provided by (used in) financing activities
Proceeds from Lines of Credit		0	0		49,980
Repayments of Lines of Credit		0	0		(49,980)
Proceeds from Issuance of Subordinated Long-term Debt		0	0		49,526
Repayments of Subordinated Debt		0	0		(34,767)
Cash received from stock option exercises			197		281
Proceeds from shares issued under the direct stock purchase plan		2,023	2,132		4,951
Common dividends paid		(62,736)	(60,840)		(53,274)
Net cash provided by (used in) financing activities		816,964	1,569,237		(336,163)
Cash and cash equivalents at beginning of year		1,296,636	150,974		250,455
Cash and cash equivalents at end of period		2,240,684	1,296,636		150,974
Payments for Repurchase of Common Stock		0	(95,091)		0
RepaymentsOfJuniorSubordinatedDebt		0	0		(13,329)
Repayments of Long-term Debt		(18,750)	(42,187)
Proceeds from Issuance of Debt					74,867
Net payments from exercise of stock options		57
Parent Company [Member]
Condensed Financial Statements, Captions [Line Items]
Investments in subsidiaries	[1]	2,952,089	1,761,383
Net income		120,992	121,167		165,175
Adjustments to reconcile net income to net cash provided by operating activities
Amortization		137	152		157
Deferred income tax expense		12	284		1,021
Change in prepaid income taxes and other assets		(229)	(475)	[2]	20,556
Change in other liabilities		(1,873)	(169)		(4,613)
Equity (deficit) in undistributed income of subsidiaries		46,571	(40,933)		(10,641)
Net cash provided by operating activities		72,468	161,892		192,937
Cash flows provided by (used) in investing activities
Net cash acquired (paid) in business combinations		119,816	0		(148,297)
Net cash used in investing activities		119,816	0		(148,297)
Cash flows provided by (used in) financing activities
Proceeds from Lines of Credit		0	0		49,980
Repayments of Lines of Credit		0	0		(49,980)
Proceeds from Issuance of Subordinated Long-term Debt		0	0		49,526
Restricted stock awards issued, net of awards surrendered		(1,249)	(1,187)		(1,463)
Cash received from stock option exercises			197		281
Proceeds from shares issued under the direct stock purchase plan		2,023	2,132		4,951
Common dividends paid		(62,736)	(60,840)		(53,274)
Net cash provided by (used in) financing activities		(80,769)	(196,976)		26,792
Net increase (decrease) in cash and cash equivalents		111,515	(35,084)		71,432
Cash and cash equivalents at beginning of year		100,604	135,688		64,256
Cash and cash equivalents at end of period		212,119	100,604		135,688
Cash	[3]	212,119	100,604
Payments for Repurchase of Common Stock		0	(95,091)		0
RepaymentsOfJuniorSubordinatedDebt		0	0		(13,329)
Repayments of Long-term Debt		(18,750)	(42,187)
Proceeds from Issuance of Debt					74,867
Reallocation of tax asset from parent to bank subsidiary, noncash adjustment			30,100
Net payments from exercise of stock options		(57)
Subordinated Debt [Member] | Parent Company [Member]
Cash flows provided by (used in) financing activities
Repayments of Subordinated Debt		$ 0	$ 0		$ (34,767)

[1] Majority of balance eliminates in consolidation

[2] Reflected in this line for the year ended December 31, 2020 is a noncash adjustment which decreased prepaid income taxes and increased investment in subsidiary by $30.1 million, which represents a reallocation of a tax asset from the parent to the bank subsidiary.

[3] Entire balance eliminates in consolidation.