Fair Value Measurements Fair Value Measurements, Financial Instruments Measured On a Recurring Basis, Quantitative Information (Details) (Fair Value, Inputs, Level 3 [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015		Dec. 31, 2014		Mar. 31, 2014
Available-for-sale securities [Member] | Municipal and other tax-exempt securities [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Inputs, Asset, Par Value	$ 10,370		$ 10,870		$ 16,295
Fair Value Inputs, Asset, Amortized Cost	10,309		10,805		16,224
Fair Value Inputs, Asset, Fair Value	9,623		10,093		15,523
Fair Value Measurements, Valuation Techniques	Discounted cash flows	[1]	Discounted cash flows	[1]	Discounted cash flows	[1]
Fair Value Measurements, Significant Unobservable Input	Interest rate spread		Interest rate spread		Interest rate spread
Fair Value Inputs, Assets, Discount Rate, Minimum	4.99%	[2]	4.96%	[3]	4.95%	[4]
Fair Value Inputs, Assets, Discount Rate, Maximum	5.29%	[2]	5.26%	[3]	5.25%	[4]
Fair Value Inputs, Assets, Discount Rate, Weighted Average	5.25%	[2]	5.21%	[3]	5.13%	[4]
Fair Value Inputs, Assets, Fair Value As Percentage of Par Value, Minimum	92.63%	[5]	92.65%	[5]	95.05%	[5]
Fair Value Inputs, Assets, Fair Value As Percentage of Par Value, Maximum	92.99%	[5]	94.32%	[5]	95.49%	[5]
Fair Value Inputs, Fair Value As Percentage of Par Value, Weighted Average	92.80%	[5]	93.09%	[5]	95.26%	[5]
Investment Grade Tax Exempt Securities Yield Spread Over Comparable Securities Minimum	491		488		468
Investment Grade Tax Exempt Securities Yield Spread Over Comparable Securities Maximum	518		516		515
Available-for-sale securities [Member] | Other debt securities [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Inputs, Asset, Par Value	4,400		4,400		4,900
Fair Value Inputs, Asset, Amortized Cost	4,400		4,400		4,900
Fair Value Inputs, Asset, Fair Value	4,150		4,150		4,712
Fair Value Measurements, Valuation Techniques	Discounted cash flows	[1]	Discounted cash flows	[1]	Discounted cash flows	[1]
Fair Value Measurements, Significant Unobservable Input	Interest rate spread		Interest rate spread		Interest rate spread
Fair Value Inputs, Assets, Discount Rate, Minimum	5.42%	[6]	5.62%	[6]	5.46%	[6]
Fair Value Inputs, Assets, Discount Rate, Maximum	5.67%	[6]	5.67%	[6]	5.66%	[6]
Fair Value Inputs, Assets, Discount Rate, Weighted Average	5.64%	[6]	5.66%	[6]	5.63%	[6]
Fair Value Inputs, Assets, Fair Value As Percentage of Par Value, Minimum	94.31%	[5]	92.65%	[5]	96.16%	[5]
Fair Value Inputs, Assets, Fair Value As Percentage of Par Value, Maximum	94.32%	[5]	92.95%	[5]	96.16%	[5]
Fair Value Inputs, Fair Value As Percentage of Par Value, Weighted Average	94.32%	[5]	92.77%	[5]	96.16%	[5]
Average Yields On Comparable Short-term Taxable Securities Maximum	1.00%		1.00%		1.00%
Residential mortgage loans held for sale [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Inputs, Asset, Amortized Cost	7,444		12,468
Fair Value Inputs, Asset, Fair Value	6,870		11,856
Fair Value Measurements, Valuation Techniques	Quoted prices of loans sold in securitization transactions, with a liquidity discount applied		Quoted prices of loans sold in securitization transactions, with a liquidity discount applied
Fair Value Measurements, Significant Unobservable Input	Liquidity discount applied to the market value of a mortgage loans qualifying for sale to U.S. government agencies.		Liquidity discount applied to the market value of a mortgage loans qualifying for sale to U.S. government agencies.
Other assets - private equity funds [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Inputs, Asset, Fair Value	$ 25,565		$ 25,627		$ 27,466
Fair Value Measurements, Valuation Techniques	Net asset value reported by underlying fund		Net asset value reported by underlying fund		Net asset value reported by underlying fund
Fair Value Measurements, Significant Unobservable Input	Net asset value reported by underlying fund		Net asset value reported by underlying fund		Net asset value reported by underlying fund

[1] Discounted cash flows developed using discount rates primarily based on reference to interest rate spreads for comparable securities of similar duration and credit rating as determined by the nationally-recognized rating agencies, adjusted for lack of trading volume

[2] Interest rate yields used to value investment grade tax-exempt securities represent a spread of 491 to 518 basis points over average yields for comparable tax-exempt securities.

[3] Interest rate yields used to value investment grade tax-exempt securities represent a spread of 488 to 516 basis points over average yields for comparable tax-exempt securities.

[4] Interest rate yields used to value investment grade tax-exempt securities represent a spread of 468 to 515 basis points over average yields for comparable tax-exempt securities.

[5] Represents fair value as a percentage of par value.

[6] Interest rate yields used to value investment grade taxable securities based on comparable short-term taxable securities which are generally yielding less than 1%.