Summary of Significant Accounting Policies - Additional Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2013	Dec. 31, 2012
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortization of intangible assets		10 years
Unrealized gain on available for sale securities	$ 2,464	$ 3,295
Minimum pension liability adjustment	$ 2,055	$ 2,055
Maximum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Written loan commitment period before closing	60 days