FDIC Indemnification Asset (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2012
FDIC indemnification asset components
Receivable related to claims submitted, not yet received	$ 41,701	$ 33,040	$ 8,828
Receivable related to estimated future claims on loans	53,054	62,044	85,859
Receivable related to estimated future claims on other real estate owned	5,839	7,475	18,718
FDIC indemnification asset, ending	$ 100,594	$ 102,559	$ 113,405