Quarterly Financial Information (Unaudited) (Schedule of Quarterly Financial Information) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Quarterly Financial Information Disclosure [Abstract]
Interest and Dividend Income, Operating	$ 237,873	$ 234,345	$ 241,801	$ 245,429	$ 251,120	$ 254,572	$ 267,778	$ 294,139	$ 959,448	$ 1,067,609	$ 1,281,870
Interest Expense	31,858	39,223	43,490	49,189	57,754	67,093	77,441	113,563	163,760	315,851	529,085
Net interest income before provision for loan losses	206,015	195,122	198,311	196,240	193,366	187,479	190,337	180,576	795,688	751,758	752,785
Provision for (recovery of) credit losses	246	(11,842)	(27,534)	(27,989)	(1,643)	29,232	25,414	125,428	(67,119)	178,431	8,904
Net interest income after provision for loan losses	205,769	206,964	225,845	224,229	195,009	158,247	164,923	55,148	862,807	573,327	743,881
Noninterest Income	45,622	25,478	32,757	30,296	35,280	36,292	38,351	23,298	134,153	133,221	147,204
Noninterest Expense	187,860	118,042	118,452	123,221	123,324	108,627	106,370	118,868	547,575	457,189	487,089
Income (Loss) from Continuing Operations before Income Taxes, Domestic	63,531	114,400	140,150	131,304	106,965	85,912	96,904	(40,422)	449,385	249,359
Provision for income taxes	(61,724)	27,459	36,176	32,490	21,228	19,353	20,396	(9,471)	34,401	51,506	90,898
Net income	$ 125,255	$ 86,941	$ 103,974	$ 98,814	$ 85,737	$ 66,559	$ 76,508	$ (30,951)	$ 414,984	$ 197,853	$ 313,098
Earnings per common share, basic	$ 1.42	$ 0.94	$ 1.12	$ 1.06	$ 0.89	$ 0.70	$ 0.80	$ (0.33)	$ 4.52	$ 2.06	$ 3.14
Earnings per common share, diluted	$ 1.41	$ 0.94	$ 1.11	$ 1.06	$ 0.89	$ 0.70	$ 0.80	$ (0.33)	$ 4.52	$ 2.06	$ 3.13
Tax Adjustments, Settlements, and Unusual Provisions	$ 43,900								$ 43,900
Condensed Cash Flow Statements, Captions [Line Items]
Gain on sale of loans, net									24,394	$ 13,170	$ 12,119
Discontinuance of cash flow hedges	(44,833)								(44,833)	$ 0	$ 0
Payments to Employees	(6,809)
Professional fees	(4,198)
Impairment, Lessor Asset under Operating Lease	(2,813)
Notable items that impacted income before income taxes	(40,437)
Tax Adjustments, Settlements, and Unusual Provisions	43,900								$ 43,900
Domestic Tax Authority
Quarterly Financial Information Disclosure [Abstract]
Tax Adjustments, Settlements, and Unusual Provisions	25,200
Condensed Cash Flow Statements, Captions [Line Items]
Tax Adjustments, Settlements, and Unusual Provisions	25,200
1-4 single family residential
Condensed Cash Flow Statements, Captions [Line Items]
Gain on sale of loans, net	$ 18,216