Fair Value Measurements - Fair Value, Financial Instruments, Unobservable Input Reconciliation (Details) (Recurring basis, USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Securities available for sale, at fair value
Level 3 Financial Instruments Measured at Fair Value
Beginning balance	$ 3,039,000	$ 3,042,000	$ 3,049,000	$ 6,763,000
Total gains (losses):
Included in other comprehensive income	3,000	5,000	(7,000)	20,000
Purchases, sales, issuances and settlements:
Purchases	0	0	0	0
Transfer in and/or out of Level 3	0	0	0	(3,736,000)
Ending Balance	3,042,000	3,047,000	3,042,000	3,047,000
Change in unrealized gains relating to assets still held at the reporting date	3,000	5,000	(7,000)	20,000
State tax credits held for sale
Level 3 Financial Instruments Measured at Fair Value
Beginning balance	19,822,000	24,836,000	23,020,000	26,350,000
Total gains (losses):
Included in earnings	317,000	264,000	422,000	994,000
Purchases, sales, issuances and settlements:
Sales	0	(31,000)	(3,303,000)	(2,275,000)
Ending Balance	20,139,000	25,069,000	20,139,000	25,069,000
Change in unrealized gains relating to assets still held at the reporting date	$ 317,000	$ 257,000	$ (456,000)	$ 439,000