Securities Fair Value Option Securities (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Schedule of Fair Value Option Securities [Line Items]
Fair Value Option Securities, Fair Value	$ 311,597	$ 167,125
Fair Value Option Securities, Net Unrealized Gain (Loss)	1,624	(8,169)
U.S. government agency residential mortgage-backed securities [Member]
Schedule of Fair Value Option Securities [Line Items]
Fair Value Option Securities, Fair Value	311,597	157,431
Fair Value Option Securities, Net Unrealized Gain (Loss)	1,624	(8,378)
Other securities [Member]
Schedule of Fair Value Option Securities [Line Items]
Fair Value Option Securities, Fair Value	0	9,694
Fair Value Option Securities, Net Unrealized Gain (Loss)	$ 0	$ 209