Fair Value Measurements (Summary of Gains and Losses on Level 3 Assets and Liabilities) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Trading Activity, Gains and Losses, Net [Line Items]
Total gains or losses included in earnings	$ 19,259	$ (2,737)
Change in unrealized gains or losses relating to assets still held at period end	836	(5,063)
Other Non-Interest Income [Member]
Trading Activity, Gains and Losses, Net [Line Items]
Total gains or losses included in earnings	122	234
Change in unrealized gains or losses relating to assets still held at period end	118	234
Investment Securities Gains (Losses), Net [Member]
Trading Activity, Gains and Losses, Net [Line Items]
Total gains or losses included in earnings	19,137	(2,971)
Change in unrealized gains or losses relating to assets still held at period end	$ 718	$ (5,297)