Securities (Details 3) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
A roll-forward of the other-than-temporary impairment amount related to credit losses
Balance of credit losses on debt securities for which a portion of other-than-temporary impairment was recognized in earnings, beginning of period	$ 4,054	$ 4,054
Additional credit loss for which other-than-temporary impairment was not previously recognized	0	0
Additional credit loss for which other-than-temporary impairment was previously recognized	0	0
Balance of credit losses on debt securities for which a portion of other-than-temporary impairment was recognized in earnings, end of period	$ 4,054	$ 4,054