Fair Value of Financial Instruments (Significant Observable Inputs used in the Valuation of Privately held Securities and Credit Default Assets) (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended	12 Months Ended
	Jun. 30, 2014	Dec. 31, 2013
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Trading securities	$ 34,129	$ 35,991
Derivative assets		52
Significant unobservable inputs
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Total	193	274
Significant unobservable inputs | Tax-exempt municipal | Discounted cash flow
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Trading securities	$ 193	$ 274
Significant unobservable inputs | Tax-exempt municipal | Discounted cash flow | Minimum
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Short and long term cash flows	0.54%	0.58%
Significant unobservable inputs | Tax-exempt municipal | Discounted cash flow | Maximum
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Short and long term cash flows	33.65%	33.68%