Other Investments (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010	Dec. 31, 2010
Federal Home Loan Bank and Federal Reserve Bank stock
Investment in FRB and FHLB stock	$ 111,100,000	$ 124,400,000	$ 111,100,000	$ 124,400,000	$ 120,700,000
FHLB stock	80,300,000		80,300,000
Private Equity and Alternative Investments
Investments carried at cost	40,117,000	36,744,000	40,117,000	36,744,000	37,454,000
Recognized impairment on cost method investments	32,000	500,000	200,000	900,000
Private equity investments
Private Equity and Alternative Investments
Investments carried at cost	23,249,000	21,031,000	23,249,000	21,031,000	21,408,000
Real estate
Private Equity and Alternative Investments
Investments carried at cost	11,112,000	9,649,000	11,112,000	9,649,000	10,053,000
Alternative Investments Measured at Fair Value on a Nonrecurring Basis
Fair Value	7,273,000		7,273,000
Unfunded Commitments	1,429,000		1,429,000
Hedge
Private Equity and Alternative Investments
Investments carried at cost	2,883,000	2,953,000	2,883,000	2,953,000	2,953,000
Other
Private Equity and Alternative Investments
Investments carried at cost	$ 2,873,000	$ 3,111,000	$ 2,873,000	$ 3,111,000	$ 3,040,000