Fair Value Measurements Changes in Assets and Liabilities Measured at Fair Value on a Recurring Basis Using Level 3 Inputs (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, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Debt Securities	$ 2,554,866,000				$ 2,554,866,000
Equity Securities, Other [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Equity Securities	6,900,000				6,900,000				6,700,000
Corporate Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Debt Securities	106,551,000				106,551,000				112,842,000
Pooled Trust Preferred Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Debt Securities	5,191,000				5,191,000				6,927,000
Single-issuer Trust Preferred Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Debt Securities	48,368,000				48,368,000				51,656,000
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Equity Securities, Other [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Equity Securities	6,900,000				6,900,000				6,700,000
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Pooled Trust Preferred Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Debt Securities	5,200,000				5,200,000				6,900,000
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	5,391,000		5,018,000		6,927,000		5,109,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales	0		0		(4,987,000)		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings	(97,000)	[1]	(19,000)	[1]	1,604,000	[1]	(19,000)	[1]
Unrealized adjustment to fair value	(103,000)	[1]	298,000	[1]	1,771,000	[1]	612,000	[1]
Settlements - calls	0		(202,000)		(124,000)		(605,000)
(Premium amortization) discount accretion	0	[2]	46,000	[2]	0	[2]	44,000	[2]
Balance, end of period	5,191,000		5,141,000		5,191,000		5,141,000
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Single-issuer Trust Preferred Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Debt Securities	3,800,000				3,800,000				3,400,000
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	3,670,000		4,100,000		3,360,000		4,180,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales	0		(956,000)		0		(956,000)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings	0	[1]	19,000	[1]	0	[1]	19,000	[1]
Unrealized adjustment to fair value	108,000	[1]	(55,000)	[1]	412,000	[1]	111,000	[1]
Settlements - calls	0		0		0		(250,000)
(Premium amortization) discount accretion	2,000	[2]	2,000	[2]	8,000	[2]	6,000	[2]
Balance, end of period	3,780,000		3,110,000		3,780,000		3,110,000
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Auction Rate Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	152,592,000		203,282,000		149,339,000		225,211,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales	(25,000)		0		(25,000)		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings	0	[1]	0	[1]	0	[1]	0	[1]
Unrealized adjustment to fair value	1,983,000	[1]	6,809,000	[1]	7,171,000	[1]	(12,677,000)	[1]
Settlements - calls	(317,000)		(50,370,000)		(2,725,000)		(54,880,000)
(Premium amortization) discount accretion	277,000	[2]	341,000	[2]	750,000	[2]	2,408,000	[2]
Balance, end of period	154,510,000		160,062,000		154,510,000		160,062,000
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Financial Institutions Subordinated Debt [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Debt Securities	50,500,000				50,500,000				51,700,000
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Single-issuer Trust Preferred Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Debt Securities	$ 44,600,000				$ 44,600,000				$ 48,300,000

[1]

[2] Included as a component of net interest income on the consolidated statements of income.