Federal and State Income Taxes (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Deferred Tax Assets, Gross [Abstract]
Deferred Tax Assets, Available for sale securities mark to market	$ 14,700,000	$ 0
Deferred Tax Assets, Stock-based compensation	8,100,000	9,100,000
Deferred Tax Assets, Credit loss allowances	75,600,000	86,100,000
Deferred Tax Assets, Valuation adjustments	35,300,000	45,100,000
Deferred Tax Assets, Deferred book income	3,500,000	7,200,000
Deferred Tax Assets, Deferred compensation	60,100,000	45,100,000
Deferred Tax Assets, Other	29,500,000	31,300,000
Deferred Tax Assets, Total	226,800,000	223,900,000
Deferred Tax Liabilities, Gross [Abstract]
Deferred Tax Liabilities, Available for sale securities mark to market	0	99,000,000
Deferred Tax Liabilities, Depreciation	17,300,000	19,600,000
Deferred Tax Liabilities, Mortgage servicing rights	72,200,000	59,500,000
Deferred Tax Liabilities, Lease financing	23,200,000	21,100,000
Deferred Tax Liabilities, Other	18,500,000	21,700,000
Deferred Tax Liabilities, Total	131,200,000	220,900,000
Deferred Tax Assets, Net	95,600,000	3,000,000
Current income tax expense [Abstract]
Current income tax expense, Federal	125,412,000	159,706,000	137,802,000
Current income tax expense, State	14,381,000	19,103,000	16,085,000
Current income tax expense, Total	139,793,000	178,809,000	153,887,000
Deferred income tax expense [Abstract]
Deferred income tax expense, Federal	15,915,000	8,664,000	3,882,000
Deferred income tax expense, State	1,590,000	1,267,000	742,000
Deferred income tax expense, Total	17,505,000	9,931,000	4,624,000
Total income tax expense	157,298,000	188,740,000	158,511,000
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Federal statutory tax	166,680,000	190,003,000	156,917,000
Tax exempt revenue	(7,361,000)	(5,558,000)	(5,357,000)
Effect of state income taxes, net of federal benefit	10,937,000	13,684,000	11,198,000
Utilization of tax credits	(8,145,000)	(5,126,000)	(2,972,000)
Bank-owned life insurance	(3,596,000)	(3,850,000)	(3,879,000)
Reduction of tax accrual	(1,400,000)	(950,000)	(1,764,000)
Other, net	183,000	537,000	4,368,000
Total	157,298,000	188,740,000	158,511,000
Effective Income Tax Rate Reconciliation, Percent [Abstract]
Federal statutory tax (in hundredths)	35.00%	35.00%	35.00%
Tax exempt revenue (in hundredths)	(1.00%)	(1.00%)	(1.00%)
Effect of state income taxes, net of federal benefit (in hundredths)	2.00%	3.00%	2.00%
Utilization of tax credits (in hundredths)	(2.00%)	(1.00%)	(1.00%)
Bank-owned life insurance (in hundredths)	(1.00%)	(1.00%)	(1.00%)
Reduction of tax accrual (in hundredths)	0.00%	0.00%	0.00%
Other, net (in hundredths)	0.00%	0.00%	1.00%
Total (in hundredths)	33.00%	35.00%	35.00%
Tax accrual reduction	1,400,000	1,000,000
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance as of January 1	12,275,000	12,230,000	11,900,000
Additions for tax for current year positions	2,730,000	3,976,000	6,390,000
Settlements during the period	0	(1,000,000)	(2,510,000)
Lapses of applicable statute of limitations	(2,947,000)	(2,931,000)	(3,550,000)
Balance as of December 31	12,058,000	12,275,000	12,230,000
Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense	1,200,000	1,200,000	1,900,000
Unrecognized Tax Benefits, Penalties and Interest Accrued	$ 2,900,000
Unrecognized Tax Benefits, Number of Reporting Periods Open for Examination, Federal	3 years
Unrecognized Tax Benefits, Number of Reporting Periods Open for Examination, State, Minimum	3 years
Unrecognized Tax Benefits, Number of Reporting Periods Open for Examination, State, Maximum	6 years