Parent company financial information (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011		Dec. 31, 2010	Dec. 31, 2009
Assets:
Cash and cash equivalents	$ 113,028	$ 128,439		$ 271,264	$ 359,322
Total assets	1,301,417	1,303,450
Liabilities and stockholders' equity:
Stockholders' equity	140,775	132,881		10,056	23,318
Total liabilities and stockholders' equity	1,301,417	1,303,450
Parent Company [Member]
Assets:
Cash and cash equivalents	119	512	[1]	343	2,663
Investment in subsidiary	140,474	132,202	[1]
Other assets	182	177	[1]
Total assets	140,775	132,891	[1]
Liabilities and stockholders' equity:
Other liabilities	0	10	[1]
Stockholders' equity	140,775	132,881
Total liabilities and stockholders' equity	$ 140,775	$ 132,891	[1]

[1] Adjusted to correct an error in the computation of the Bank's regulatory capital at December 31, 2011. See Note 16 to the Company's condensed consolidated financial statements included in the Company's Quarterly Report on Form 10-Q for the quarter ended June 30, 2012.