Fair Value Accounting - Impact to Earnings from Assets and Liabilities Measured at Fair Value (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2012		Sep. 30, 2011		Sep. 30, 2012		Sep. 30, 2011
Fair Value, Measured on Recurring and Nonrecurring Basis, Gain (Loss) Included in Earnings [Line Items]
Liabilities measured on nonrecurring basis, gain (loss) included in other income	$ 0	[1]	$ 0	[1]	$ 0	[1]	$ 150	[1]
Fair value, measured on recurring and nonrecurring basis, gain (loss) included in earnings	0	[2]	177	[2]	0	[2]	675	[2]
Collateralized Mortgage Backed Securities [Member]
Fair Value, Measured on Recurring and Nonrecurring Basis, Gain (Loss) Included in Earnings [Line Items]
Assets measured on recurring basis, gain (loss) included in other income	0		396		0		1,731
Trading Securities [Member] | Mortgage-backed Securities, Issued by Private Enterprises [Member]
Fair Value, Measured on Recurring and Nonrecurring Basis, Gain (Loss) Included in Earnings [Line Items]
Assets measured on recurring basis, gain (loss) included in other income	$ 0		$ (219)		$ 0		$ (1,206)

[1] The contingent consideration represents the estimated fair value of the additional potential earn-out opportunity payable in connection with the acquisition of Corvisa that is contingent and based upon certain future earnings targets.

[2] The Company did not have any impairments relating to mortgage securities – available-for-sale or fair value adjustments relating to the contingent consideration for the nine and three months ended September 30, 2012 and 2011.