Securities Available for Sale and Held to Maturity - Gains and Losses as a Result of Calls and Disposition of Securities (Details) - Available for Sale [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Gains (losses) on Investments [Abstract]
Proceeds from calls and sales of securities	$ 0	$ 56,815	$ 224,853
Gross realized gains	0	456	1,680
Gross realized losses	$ 0	$ (156)	$ (1,195)