Variable Interest Entities (Details) (USD $)	Jun. 30, 2011	Dec. 31, 2010	Jun. 30, 2010
Variable Interest Entities
Affordable housing investments	$ 113,486,000	$ 99,670,000	$ 101,999,000
Unfunded commitments for affordable housing investments	32,100,000
Number of significant variable interest in affordable housing partnerships	4
Maximum exposure to loss	3,700,000
Aggregate carrying value of variable interest entities	$ 38,300,000	$ 37,500,000	$ 37,500,000