Fair Value Measurements (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 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	39,943,000		39,943,000		41,112,000
Net (losses) gains recognized for assets measured at fair value on nonrecurring basis
Total net losses recognized	(1,939,000)	(6,541,000)	(5,060,000)	(22,973,000)
Significant Other Observable Inputs Level 2 | Maximum
Assets
Percent of total assets	1.00%		1.00%
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	48,655,000		48,655,000		115,059,000
Derivatives assets	40,066,000		40,066,000		67,496,000
Total assets at fair value	7,133,292,000		7,133,292,000		9,388,544,000
Percent of total assets	26.00%		26.00%		33.00%
Liabilities
Derivatives liabilities	38,771,000		38,771,000		64,432,000
Contingent consideration liability	48,800,000		48,800,000		47,724,000
FDIC clawback liability	11,053,000		11,053,000		9,970,000
Other liabilities	319,000		319,000		368,000
Total liabilities at fair value	98,943,000		98,943,000		122,494,000
Redeemable noncontrolling interest	39,943,000		39,943,000		41,112,000
Measured on a Recurring Basis | Fair Value | U.S. Treasury
Assets
Securities available-for-sale	30,285,000		30,285,000		20,397,000
Measured on a Recurring Basis | Fair Value | Federal agency - Debt
Assets
Securities available-for-sale	980,025,000		980,025,000		2,349,202,000
Measured on a Recurring Basis | Fair Value | Federal agency - MBS
Assets
Securities available-for-sale	438,182,000		438,182,000		693,032,000
Measured on a Recurring Basis | Fair Value | CMOs - Federal agency
Assets
Securities available-for-sale	4,728,613,000		4,728,613,000		5,318,253,000
Measured on a Recurring Basis | Fair Value | CMOs - Non-agency
Assets
Securities available-for-sale	45,327,000		45,327,000		61,513,000
Measured on a Recurring Basis | Fair Value | State and municipal
Assets
Securities available-for-sale	466,760,000		466,760,000		454,474,000
Measured on a Recurring Basis | Fair Value | Other debt securities
Assets
Securities available-for-sale	350,244,000		350,244,000		307,417,000
Measured on a Recurring Basis | Fair Value | Equity securities and mutual funds
Assets
Securities available-for-sale	5,135,000		5,135,000		1,701,000
Measured on a Recurring Basis | Quoted Prices in Active Markets Level 1
Assets
Trading securities	38,411,000		38,411,000		113,010,000
Derivatives assets	1,963,000		1,963,000		218,000
Total assets at fair value	75,794,000		75,794,000		135,326,000
Liabilities
Derivatives liabilities	2,490,000		2,490,000
Total liabilities at fair value	2,490,000		2,490,000
Measured on a Recurring Basis | Quoted Prices in Active Markets Level 1 | U.S. Treasury
Assets
Securities available-for-sale	30,285,000		30,285,000		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	5,135,000		5,135,000		1,701,000
Measured on a Recurring Basis | Significant Other Observable Inputs Level 2
Assets
Trading securities	10,244,000		10,244,000		2,049,000
Derivatives assets	38,103,000		38,103,000		67,278,000
Total assets at fair value	6,995,659,000		6,995,659,000		9,188,031,000
Liabilities
Derivatives liabilities	36,281,000		36,281,000		64,432,000
Other liabilities	319,000		319,000		368,000
Total liabilities at fair value	36,600,000		36,600,000		64,800,000
Measured on a Recurring Basis | Significant Other Observable Inputs Level 2 | Federal agency - Debt
Assets
Securities available-for-sale	980,025,000		980,025,000		2,349,202,000
Measured on a Recurring Basis | Significant Other Observable Inputs Level 2 | Federal agency - MBS
Assets
Securities available-for-sale	438,182,000		438,182,000		693,032,000
Measured on a Recurring Basis | Significant Other Observable Inputs Level 2 | CMOs - Federal agency
Assets
Securities available-for-sale	4,728,613,000		4,728,613,000		5,318,253,000
Measured on a Recurring Basis | Significant Other Observable Inputs Level 2 | CMOs - Non-agency
Assets
Securities available-for-sale	45,327,000		45,327,000		61,513,000
Measured on a Recurring Basis | Significant Other Observable Inputs Level 2 | State and municipal
Assets
Securities available-for-sale	420,594,000		420,594,000		407,429,000
Measured on a Recurring Basis | Significant Other Observable Inputs Level 2 | Other debt securities
Assets
Securities available-for-sale	334,571,000		334,571,000		289,275,000
Measured on a Recurring Basis | Significant Unobservable Inputs Level 3
Assets
Total assets at fair value	61,839,000		61,839,000		65,187,000
Fair value of senior notes	15,700,000		15,700,000
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	48,800,000		48,800,000		47,724,000
FDIC clawback liability	11,053,000		11,053,000		9,970,000
Total liabilities at fair value	59,853,000		59,853,000		57,694,000
Redeemable noncontrolling interest	39,943,000		39,943,000		41,112,000
Measured on a Recurring Basis | Significant Unobservable Inputs Level 3 | State and municipal
Assets
Securities available-for-sale	46,166,000		46,166,000		47,045,000
Measured on a Recurring Basis | Significant Unobservable Inputs Level 3 | Other debt securities
Assets
Securities available-for-sale	15,673,000		15,673,000		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:				(367,000)
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:	148,000	(1,572,000)	293,000	(1,937,000)
Measured on a Nonrecurring Basis | Residential mortgage
Net (losses) gains recognized for assets measured at fair value on nonrecurring basis
Collateral dependent impaired loans:	(230,000)	(540,000)	(221,000)	(1,122,000)
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:		(281,000)		(6,753,000)
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:		(115,000)	116,000	(62,000)
Measured on a Nonrecurring Basis | Installment loan
Net (losses) gains recognized for assets measured at fair value on nonrecurring basis
Collateral dependent impaired loans:			(138,000)	(107,000)
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	(1,857,000)	(3,700,000)	(4,711,000)	(12,165,000)
Total net losses recognized on covered assets	1,900,000	3,500,000	4,700,000	11,000,000
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		(333,000)	(399,000)	(460,000)
Measured on a Nonrecurring Basis | Fair Value
Assets
Total assets at fair value	28,985,000		28,985,000		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	17,000		17,000		2,655,000
Measured on a Nonrecurring Basis | Fair Value | Commercial real estate mortgages
Assets
Collateral dependent impaired loans	7,300,000		7,300,000		10,963,000
Measured on a Nonrecurring Basis | Fair Value | Residential mortgage
Assets
Collateral dependent impaired loans	1,457,000		1,457,000		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	19,525,000		19,525,000		44,396,000
Measured on a Nonrecurring Basis | Fair Value | Private equity and alternative investments
Assets
Total assets at fair value	686,000		686,000		6,178,000
Measured on a Nonrecurring Basis | Significant Other Observable Inputs Level 2
Assets
Total assets at fair value	16,494,000		16,494,000		39,124,000
Measured on a Nonrecurring Basis | Significant Other Observable Inputs Level 2 | Commercial real estate mortgages
Assets
Collateral dependent impaired loans					3,950,000
Measured on a Nonrecurring Basis | Significant Other Observable Inputs Level 2 | Installment loan
Assets
Collateral dependent impaired loans					550,000
Measured on a Nonrecurring Basis | Significant Other Observable Inputs Level 2 | Other real estate owned
Assets
Total assets at fair value	16,494,000		16,494,000		34,624,000
Measured on a Nonrecurring Basis | Significant Unobservable Inputs Level 3
Assets
Total assets at fair value	12,491,000		12,491,000		36,127,000
Measured on a Nonrecurring Basis | Significant Unobservable Inputs Level 3 | Commercial
Assets
Collateral dependent impaired loans	17,000		17,000		2,655,000
Measured on a Nonrecurring Basis | Significant Unobservable Inputs Level 3 | Commercial real estate mortgages
Assets
Collateral dependent impaired loans	7,300,000		7,300,000		7,013,000
Measured on a Nonrecurring Basis | Significant Unobservable Inputs Level 3 | Residential mortgage
Assets
Collateral dependent impaired loans	1,457,000		1,457,000		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 | Other real estate owned
Assets
Total assets at fair value	3,031,000		3,031,000		9,772,000
Measured on a Nonrecurring Basis | Significant Unobservable Inputs Level 3 | Private equity and alternative investments
Assets
Total assets at fair value	$ 686,000		$ 686,000		$ 6,178,000