Fair Value Measurements (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Fair Value Measurements
Fair value of assets transfers from Level 1 to Level 2	$ 0
Fair value of assets transfers from Level 2 to Level 1	0
Fair value of liabilities transfers from Level 1 to Level 2	0
Fair value of liabilities transfers from Level 2 to Level 1	0
Assets
Securities available-for-sale	6,241,117,000	9,205,989,000
Trading securities	82,357,000	115,059,000
Assets purchases 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	39,768,000	41,112,000
U.S. Treasury
Assets
Securities available-for-sale	35,335,000	20,397,000
Federal agency - Debt
Assets
Securities available-for-sale	1,410,536,000	2,349,202,000
Federal agency - MBS
Assets
Securities available-for-sale	157,226,000	693,032,000
CMOs - Federal agency
Assets
Securities available-for-sale	3,997,298,000	5,318,253,000
CMOs - Non-agency
Assets
Securities available-for-sale	37,462,000	61,513,000
State and municipal
Assets
Securities available-for-sale	415,995,000	454,474,000
Other debt securities
Assets
Securities available-for-sale	178,822,000	307,417,000
Equity securities and mutual funds
Assets
Securities available-for-sale	8,443,000	1,701,000
Measured on a Recurring Basis | Fair Value
Assets
Trading securities	82,357,000	115,059,000
Derivatives assets	34,613,000	67,496,000
Total assets at fair value	6,358,087,000	9,388,544,000
Percent of total assets	21.00%	33.00%
Liabilities
Derivatives liabilities	32,970,000	64,432,000
Contingent consideration liability	49,900,000	47,724,000
FDIC clawback liability	11,967,000	9,970,000
Other liabilities	1,044,000	368,000
Total liabilities at fair value	95,881,000	122,494,000
Redeemable noncontrolling interest	39,768,000	41,112,000
Measured on a Recurring Basis | Fair Value | U.S. Treasury
Assets
Securities available-for-sale	35,335,000	20,397,000
Measured on a Recurring Basis | Fair Value | Federal agency - Debt
Assets
Securities available-for-sale	1,410,536,000	2,349,202,000
Measured on a Recurring Basis | Fair Value | Federal agency - MBS
Assets
Securities available-for-sale	157,226,000	693,032,000
Measured on a Recurring Basis | Fair Value | CMOs - Federal agency
Assets
Securities available-for-sale	3,997,298,000	5,318,253,000
Measured on a Recurring Basis | Fair Value | CMOs - Non-agency
Assets
Securities available-for-sale	37,462,000	61,513,000
Measured on a Recurring Basis | Fair Value | State and municipal
Assets
Securities available-for-sale	415,995,000	454,474,000
Measured on a Recurring Basis | Fair Value | Other debt securities
Assets
Securities available-for-sale	178,822,000	307,417,000
Measured on a Recurring Basis | Fair Value | Equity securities and mutual funds
Assets
Securities available-for-sale	8,443,000	1,701,000
Measured on a Recurring Basis | Quoted Prices in Active Markets Level 1
Assets
Trading securities	80,659,000	113,010,000
Derivatives assets	3,487,000	218,000
Total assets at fair value	127,924,000	135,326,000
Liabilities
Derivatives liabilities	3,333,000
Total liabilities at fair value	3,333,000
Measured on a Recurring Basis | Quoted Prices in Active Markets Level 1 | U.S. Treasury
Assets
Securities available-for-sale	35,335,000	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	8,443,000	1,701,000
Measured on a Recurring Basis | Significant Other Observable Inputs Level 2
Assets
Trading securities	1,698,000	2,049,000
Derivatives assets	31,126,000	67,278,000
Total assets at fair value	6,226,530,000	9,188,031,000
Liabilities
Derivatives liabilities	29,637,000	64,432,000
Other liabilities	1,044,000	368,000
Total liabilities at fair value	30,681,000	64,800,000
Measured on a Recurring Basis | Significant Other Observable Inputs Level 2 | Federal agency - Debt
Assets
Securities available-for-sale	1,410,536,000	2,349,202,000
Measured on a Recurring Basis | Significant Other Observable Inputs Level 2 | Federal agency - MBS
Assets
Securities available-for-sale	157,226,000	693,032,000
Measured on a Recurring Basis | Significant Other Observable Inputs Level 2 | CMOs - Federal agency
Assets
Securities available-for-sale	3,997,298,000	5,318,253,000
Measured on a Recurring Basis | Significant Other Observable Inputs Level 2 | CMOs - Non-agency
Assets
Securities available-for-sale	37,462,000	61,513,000
Measured on a Recurring Basis | Significant Other Observable Inputs Level 2 | State and municipal
Assets
Securities available-for-sale	412,362,000	407,429,000
Measured on a Recurring Basis | Significant Other Observable Inputs Level 2 | Other debt securities
Assets
Securities available-for-sale	178,822,000	289,275,000
Measured on a Recurring Basis | Significant Unobservable Inputs Level 3
Assets
Total assets at fair value	3,633,000	65,187,000
Liabilities
Contingent consideration liability	49,900,000	47,724,000
FDIC clawback liability	11,967,000	9,970,000
Total liabilities at fair value	61,867,000	57,694,000
Redeemable noncontrolling interest	39,768,000	41,112,000
Measured on a Recurring Basis | Significant Unobservable Inputs Level 3 | State and municipal
Assets
Securities available-for-sale	3,633,000	47,045,000
Measured on a Recurring Basis | Significant Unobservable Inputs Level 3 | Other debt securities
Assets
Securities available-for-sale		18,142,000
Measured on a Nonrecurring Basis
Net (losses) gains recognized for assets measured at fair value on nonrecurring basis
Total net losses recognized	(7,571,000)	(31,847,000)
Measured on a Nonrecurring Basis | Commercial
Net (losses) gains recognized for assets measured at fair value on nonrecurring basis
Collateral dependent impaired loans:	(15,000)	(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:	(641,000)	(1,143,000)
Measured on a Nonrecurring Basis | Residential mortgage
Net (losses) gains recognized for assets measured at fair value on nonrecurring basis
Collateral dependent impaired loans:	(469,000)	(975,000)
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:		(5,137,000)
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:	116,000	(25,000)
Measured on a Nonrecurring Basis | Installment
Net (losses) gains recognized for assets measured at fair value on nonrecurring basis
Collateral dependent impaired loans:	(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	(5,892,000)	(20,695,000)
Total net losses recognized on covered assets	4,700,000	17,700,000
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	(532,000)	(3,296,000)
Measured on a Nonrecurring Basis | Fair Value
Assets
Total assets at fair value	21,666,000	75,251,000
Measured on a Nonrecurring Basis | Fair Value | Commercial
Assets
Collateral dependent impaired loans		2,655,000
Measured on a Nonrecurring Basis | Fair Value | Commercial real estate mortgages
Assets
Collateral dependent impaired loans	1,220,000	10,963,000
Measured on a Nonrecurring Basis | Fair Value | Residential mortgage
Assets
Collateral dependent impaired loans	1,300,000	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
Assets
Collateral dependent impaired loans		550,000
Measured on a Nonrecurring Basis | Fair Value | Other real estate owned
Assets
Total assets at fair value	18,251,000	44,396,000
Measured on a Nonrecurring Basis | Fair Value | Private equity and alternative investments
Assets
Total assets at fair value	895,000	6,178,000
Measured on a Nonrecurring Basis | Significant Unobservable Inputs Level 3
Assets
Total assets at fair value	21,666,000	75,251,000
Measured on a Nonrecurring Basis | Significant Unobservable Inputs Level 3 | Maximum
Assets
Percent of total assets	1.00%	1.00%
Measured on a Nonrecurring Basis | Significant Unobservable Inputs Level 3 | Commercial
Assets
Collateral dependent impaired loans		2,655,000
Measured on a Nonrecurring Basis | Significant Unobservable Inputs Level 3 | Commercial real estate mortgages
Assets
Collateral dependent impaired loans	1,220,000	10,963,000
Measured on a Nonrecurring Basis | Significant Unobservable Inputs Level 3 | Residential mortgage
Assets
Collateral dependent impaired loans	1,300,000	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
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	18,251,000	44,396,000
Measured on a Nonrecurring Basis | Significant Unobservable Inputs Level 3 | Private equity and alternative investments
Assets
Total assets at fair value	$ 895,000	$ 6,178,000