Fair Value Measurements Fair Value Measurements, Financial Instruments Measured On a Recurring Basis, Quantitative Information (Details) - Fair Value, Measurements, Recurring [Member] - Fair Value, Inputs, Level 3 [Member] - USD ($) $ in Thousands	9 Months Ended				12 Months Ended
	Sep. 30, 2015		Sep. 30, 2014		Dec. 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		$ 10,970		$ 10,870
Fair Value Inputs, Asset, Amortized Cost	10,310		10,904		10,805
Fair Value Inputs, Asset, Fair Value	$ 9,600		$ 10,193		$ 10,093
Fair Value Measurements, Valuation Techniques	Discounted cash flows	[1]	Discounted cash flows	[2]	Discounted cash flows	[3]
Fair Value Measurements, Significant Unobservable Input	Interest rate spread		Interest rate spread		Interest rate spread
Fair Value Inputs, Assets, Discount Rate, Minimum	5.23%	[4]	4.93%	[5]	4.96%	[6]
Fair Value Inputs, Assets, Discount Rate, Maximum	5.53%	[4]	5.23%	[5]	5.26%	[6]
Fair Value Inputs, Assets, Discount Rate, Weighted Average	5.49%	[4]	5.19%	[5]	5.21%	[6]
Fair Value Inputs, Assets, Fair Value As Percentage of Par Value, Minimum	92.35%	[7]	92.68%	[8]	92.65%	[9]
Fair Value Inputs, Assets, Fair Value As Percentage of Par Value, Maximum	92.73%	[7]	94.32%	[8]	94.32%	[9]
Fair Value Inputs, Fair Value As Percentage of Par Value, Weighted Average	92.57%	[7]	93.13%	[8]	93.09%	[9]
Investment Grade Tax Exempt Securities Yield Spread Over Comparable Securities Minimum	510		482		488
Investment Grade Tax Exempt Securities Yield Spread Over Comparable Securities Maximum	538		514		516
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		$ 4,400
Fair Value Inputs, Asset, Amortized Cost	4,400		4,400		4,400
Fair Value Inputs, Asset, Fair Value	$ 4,150		$ 4,150		$ 4,150
Fair Value Measurements, Valuation Techniques	Discounted cash flows	[1]	Discounted cash flows	[2]	Discounted cash flows	[3]
Fair Value Measurements, Significant Unobservable Input	Interest rate spread		Interest rate spread		Interest rate spread
Fair Value Inputs, Assets, Discount Rate, Minimum	5.65%	[10]	5.61%	[11]	5.62%	[12]
Fair Value Inputs, Assets, Discount Rate, Maximum	5.70%	[10]	5.65%	[11]	5.67%	[12]
Fair Value Inputs, Assets, Discount Rate, Weighted Average	5.69%	[10]	5.65%	[11]	5.66%	[12]
Fair Value Inputs, Assets, Fair Value As Percentage of Par Value, Minimum	94.32%	[7]	92.68%	[8]	92.65%	[9]
Fair Value Inputs, Assets, Fair Value As Percentage of Par Value, Maximum	94.33%	[7]	92.99%	[8]	92.95%	[9]
Fair Value Inputs, Fair Value As Percentage of Par Value, Weighted Average	94.33%	[7]	92.80%	[8]	92.77%	[9]
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	$ 8,538		$ 7,764		$ 12,468
Fair Value Inputs, Asset, Fair Value	$ 8,033		$ 7,376		$ 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		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.		Liquidity discount applied to the market value of a mortgage loans qualifying for sale to U.S. government agencies.
Liquidity Discount on Mortgage Loans Qualifying for Sale to US Govt Agencies	94.09%		95.00%		95.09%
Other assets - private equity funds [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Inputs, Asset, Fair Value	$ 24,133		$ 27,118		$ 25,627
Fair Value Measurements, Valuation Techniques	Net asset value reported by underlying funds		Net asset value reported by underlying funds		Net asset value reported by underlying funds
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] 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

[3] 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

[4] Interest rate yields used to value investment grade tax-exempt securities represent a spread of 510 to 538 basis points over average yields for comparable tax-exempt securities.

[5] Interest rate yields used to value investment grade tax-exempt securities represent a spread of 482 to 514 basis points over average yields for comparable tax-exempt securities.

[6] 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.

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

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

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

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

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

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