Fair Value Measurements (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Fair Value Measurements
Fair value of assets transfers from Level 1 to Level 2	$ 0		$ 0
Fair value of assets transfers from Level 2 to Level 1	0		0
Fair value of liabilities transfers from Level 1 to Level 2	0		0
Fair value of liabilities transfers from Level 2 to Level 1	0		0
Assets
Assets purchases measured on fair value of Level 3 on a recurring basis			0	0
Assets sales measured on fair value of Level 3 on a recurring basis			0	0
Fair value of assets transfers out of Level 3			0	0
Liabilities
Redeemable noncontrolling interest	39,840,000		39,840,000		41,112,000
Net (losses) gains recognized for assets measured at fair value on nonrecurring basis
Total net losses recognized	(1,409,000)	(6,304,000)	(6,470,000)	(29,278,000)
Significant Unobservable Inputs Level 3 | Maximum
Assets
Percent of total assets	1.00%		1.00%		1.00%
Measured on a Recurring Basis | Fair Value
Assets
Trading securities	51,451,000		51,451,000		115,059,000
Derivatives assets	44,634,000		44,634,000		67,496,000
Total assets at fair value	6,991,215,000		6,991,215,000		9,388,544,000
Percent of total assets	24.00%		24.00%		33.00%
Liabilities
Derivatives liabilities	42,584,000		42,584,000		64,432,000
Contingent consideration liability	49,350,000		49,350,000		47,724,000
FDIC clawback liability	11,279,000		11,279,000		9,970,000
Other liabilities	919,000		919,000		368,000
Total liabilities at fair value	104,132,000		104,132,000		122,494,000
Redeemable noncontrolling interest	39,840,000		39,840,000		41,112,000
Measured on a Recurring Basis | Fair Value | U.S. Treasury
Assets
Securities available-for-sale	35,425,000		35,425,000		20,397,000
Measured on a Recurring Basis | Fair Value | Federal agency - Debt
Assets
Securities available-for-sale	1,002,447,000		1,002,447,000		2,349,202,000
Measured on a Recurring Basis | Fair Value | Federal agency - MBS
Assets
Securities available-for-sale	197,173,000		197,173,000		693,032,000
Measured on a Recurring Basis | Fair Value | CMOs - Federal agency
Assets
Securities available-for-sale	4,742,584,000		4,742,584,000		5,318,253,000
Measured on a Recurring Basis | Fair Value | CMOs - Non-agency
Assets
Securities available-for-sale	43,312,000		43,312,000		61,513,000
Measured on a Recurring Basis | Fair Value | State and municipal
Assets
Securities available-for-sale	475,786,000		475,786,000		454,474,000
Measured on a Recurring Basis | Fair Value | Other debt securities
Assets
Securities available-for-sale	392,356,000		392,356,000		307,417,000
Measured on a Recurring Basis | Fair Value | Equity securities and mutual funds
Assets
Securities available-for-sale	6,047,000		6,047,000		1,701,000
Measured on a Recurring Basis | Quoted Prices in Active Markets Level 1
Assets
Trading securities	48,744,000		48,744,000		113,010,000
Derivatives assets	4,213,000		4,213,000		218,000
Total assets at fair value	94,429,000		94,429,000		135,326,000
Liabilities
Derivatives liabilities	3,577,000		3,577,000
Total liabilities at fair value	3,577,000		3,577,000
Measured on a Recurring Basis | Quoted Prices in Active Markets Level 1 | U.S. Treasury
Assets
Securities available-for-sale	35,425,000		35,425,000		20,397,000
Measured on a Recurring Basis | Quoted Prices in Active Markets Level 1 | Equity securities and mutual funds
Assets
Securities available-for-sale	6,047,000		6,047,000		1,701,000
Measured on a Recurring Basis | Significant Other Observable Inputs Level 2
Assets
Trading securities	2,707,000		2,707,000		2,049,000
Derivatives assets	40,421,000		40,421,000		67,278,000
Total assets at fair value	6,835,198,000		6,835,198,000		9,188,031,000
Liabilities
Derivatives liabilities	39,007,000		39,007,000		64,432,000
Other liabilities	919,000		919,000		368,000
Total liabilities at fair value	39,926,000		39,926,000		64,800,000
Measured on a Recurring Basis | Significant Other Observable Inputs Level 2 | Federal agency - Debt
Assets
Securities available-for-sale	1,002,447,000		1,002,447,000		2,349,202,000
Measured on a Recurring Basis | Significant Other Observable Inputs Level 2 | Federal agency - MBS
Assets
Securities available-for-sale	197,173,000		197,173,000		693,032,000
Measured on a Recurring Basis | Significant Other Observable Inputs Level 2 | CMOs - Federal agency
Assets
Securities available-for-sale	4,742,584,000		4,742,584,000		5,318,253,000
Measured on a Recurring Basis | Significant Other Observable Inputs Level 2 | CMOs - Non-agency
Assets
Securities available-for-sale	43,312,000		43,312,000		61,513,000
Measured on a Recurring Basis | Significant Other Observable Inputs Level 2 | State and municipal
Assets
Securities available-for-sale	429,570,000		429,570,000		407,429,000
Measured on a Recurring Basis | Significant Other Observable Inputs Level 2 | Other debt securities
Assets
Securities available-for-sale	376,984,000		376,984,000		289,275,000
Measured on a Recurring Basis | Significant Unobservable Inputs Level 3
Assets
Total assets at fair value	61,588,000		61,588,000		65,187,000
Prepayment rate (as a percent)			2.00%
Default rate of performing collateral (as a percent)			0.75%
Recovery Rate (as a percent)			15.00%
Recovery Rate lag time			2 years
Liabilities
Contingent consideration liability	49,350,000		49,350,000		47,724,000
FDIC clawback liability	11,279,000		11,279,000		9,970,000
Total liabilities at fair value	60,629,000		60,629,000		57,694,000
Redeemable noncontrolling interest	39,840,000		39,840,000		41,112,000
Measured on a Recurring Basis | Significant Unobservable Inputs Level 3 | State and municipal
Assets
Securities available-for-sale	46,216,000		46,216,000		47,045,000
Measured on a Recurring Basis | Significant Unobservable Inputs Level 3 | Other debt securities
Assets
Securities available-for-sale	15,372,000		15,372,000		18,142,000
Measured on a Nonrecurring Basis | Commercial
Net (losses) gains recognized for assets measured at fair value on nonrecurring basis
Collateral dependent impaired loans:				(368,000)
Measured on a Nonrecurring Basis | Commercial real estate mortgages
Net (losses) gains recognized for assets measured at fair value on nonrecurring basis
Collateral dependent impaired loans:	(934,000)	306,000	(641,000)	(1,630,000)
Measured on a Nonrecurring Basis | Residential mortgage
Net (losses) gains recognized for assets measured at fair value on nonrecurring basis
Collateral dependent impaired loans:	(2,000)	(31,000)	(224,000)	(1,152,000)
Measured on a Nonrecurring Basis | Real estate construction
Net (losses) gains recognized for assets measured at fair value on nonrecurring basis
Collateral dependent impaired loans:		130,000		(6,623,000)
Measured on a Nonrecurring Basis | Home equity loans and lines of credit
Net (losses) gains recognized for assets measured at fair value on nonrecurring basis
Collateral dependent impaired loans:		16,000	116,000	(47,000)
Measured on a Nonrecurring Basis | Installment loan
Net (losses) gains recognized for assets measured at fair value on nonrecurring basis
Collateral dependent impaired loans:		(101,000)	(138,000)	(208,000)
Measured on a Nonrecurring Basis | Other real estate owned
Net (losses) gains recognized for assets measured at fair value on nonrecurring basis
Total net losses recognized	(364,000)	(4,147,000)	(5,075,000)	(16,312,000)
Total net losses recognized on covered assets	400,000	3,600,000	5,000,000	14,700,000
Measured on a Nonrecurring Basis | Private equity and alternative investments
Net (losses) gains recognized for assets measured at fair value on nonrecurring basis
Total net losses recognized	(109,000)	(2,477,000)	(508,000)	(2,938,000)
Measured on a Nonrecurring Basis | Fair Value
Assets
Total assets at fair value	19,973,000		19,973,000		75,251,000
Measured on a Nonrecurring Basis | Fair Value | Maximum
Assets
Percent of total assets	1.00%		1.00%		1.00%
Measured on a Nonrecurring Basis | Fair Value | Commercial
Assets
Collateral dependent impaired loans	15,000		15,000		2,655,000
Measured on a Nonrecurring Basis | Fair Value | Commercial real estate mortgages
Assets
Collateral dependent impaired loans	1,214,000		1,214,000		10,963,000
Measured on a Nonrecurring Basis | Fair Value | Residential mortgage
Assets
Collateral dependent impaired loans	1,442,000		1,442,000		1,811,000
Measured on a Nonrecurring Basis | Fair Value | Real estate construction
Assets
Collateral dependent impaired loans					7,918,000
Measured on a Nonrecurring Basis | Fair Value | Home equity loans and lines of credit
Assets
Collateral dependent impaired loans					780,000
Measured on a Nonrecurring Basis | Fair Value | Installment loan
Assets
Collateral dependent impaired loans					550,000
Measured on a Nonrecurring Basis | Fair Value | Other real estate owned
Assets
Total assets at fair value	16,383,000		16,383,000		44,396,000
Measured on a Nonrecurring Basis | Fair Value | Private equity and alternative investments
Assets
Total assets at fair value	919,000		919,000		6,178,000
Measured on a Nonrecurring Basis | Significant Unobservable Inputs Level 3
Assets
Total assets at fair value	19,973,000		19,973,000		75,251,000
Measured on a Nonrecurring Basis | Significant Unobservable Inputs Level 3 | Commercial
Assets
Collateral dependent impaired loans	15,000		15,000		2,655,000
Measured on a Nonrecurring Basis | Significant Unobservable Inputs Level 3 | Commercial real estate mortgages
Assets
Collateral dependent impaired loans	1,214,000		1,214,000		10,963,000
Measured on a Nonrecurring Basis | Significant Unobservable Inputs Level 3 | Residential mortgage
Assets
Collateral dependent impaired loans	1,442,000		1,442,000		1,811,000
Measured on a Nonrecurring Basis | Significant Unobservable Inputs Level 3 | Real estate construction
Assets
Collateral dependent impaired loans					7,918,000
Measured on a Nonrecurring Basis | Significant Unobservable Inputs Level 3 | Home equity loans and lines of credit
Assets
Collateral dependent impaired loans					780,000
Measured on a Nonrecurring Basis | Significant Unobservable Inputs Level 3 | Installment loan
Assets
Collateral dependent impaired loans					550,000
Measured on a Nonrecurring Basis | Significant Unobservable Inputs Level 3 | Other real estate owned
Assets
Total assets at fair value	16,383,000		16,383,000		44,396,000
Measured on a Nonrecurring Basis | Significant Unobservable Inputs Level 3 | Private equity and alternative investments
Assets
Total assets at fair value	$ 919,000		$ 919,000		$ 6,178,000