Investment Securities (Changes in Recorded Credit Losses) (Details) (USD $) In Thousands	6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010
Investment Securities
Balance at January 1	$ 7,542	$ 2,473
Credit losses on debt securities for which impairment was not previously recognized	53	88
Credit losses on debt securities for which impairment was previously recognized	871	2,045
Increase in expected cash flows that are recognized over remaining life of security	(53)
Balance at June 30	$ 8,413	$ 4,606