Investment Securities (Credit Losses on Impaired Securities) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Roll Forward]
OTTI credit losses on previously impaired securities	$ 4	$ 85	$ 4	$ 381
Securities Available for Sale
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Roll Forward]
Beginning balance	1,863	1,528	1,863	1,232
OTTI credit losses on previously impaired securities	4	85	4	381
Ending balance	$ 1,867	$ 1,613	$ 1,867	$ 1,613