Fair Value Measurements Changes in Assets and Liabilities Measured at Fair Value on a Recurring Basis Using Level 3 Inputs (Details) (Fair Value, Measurements, Recurring [Member], Fair Value, Inputs, Level 3 [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013		Mar. 31, 2012
Pooled Trust Preferred Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	$ 6,927		$ 5,109
Unrealized adjustment to fair value	1,429	[1]	177	[1]
Settlements - calls	0		(223)
(Premium amortization) discount accretion	0	[2]	(1)	[2]
Balance, end of period	8,356		5,062
Single-issuer Trust Preferred Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	3,360		4,180
Unrealized adjustment to fair value	7	[1]	178	[1]
Settlements - calls	0		0
(Premium amortization) discount accretion	3	[2]	2	[2]
Balance, end of period	3,370		4,360
Auction Rate Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	149,339		225,211
Unrealized adjustment to fair value	5,360	[1]	(2,164)	[1]
Settlements - calls	(342)		(317)
(Premium amortization) discount accretion	282	[2]	1,147	[2]
Balance, end of period	$ 154,639		$ 223,877

[1] Pooled trust preferred securities, single-issuer trust preferred securities and ARCs are classified as available for sale investment securities; as such, the unrealized adjustment to fair value was recorded as an unrealized holding gain (loss) and included as a component of available for sale investment securities on the consolidated balance sheet.

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