Investment Information (Other Than Temporary Impairments Rollforward) (Details) (USD $)	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Disclosure Investment Information [Abstract]
Portion of OTTI not related to credit losses	$ 13,000,000
Rollforward:
Balance at start of period	62,001,000	66,545,000
Credit loss impairments recognized on securities not previously impaired	33,000	212,000
Credit loss impairments recognized on securities previously impaired	2,000	811,000
Reductions for increases in cash flows expected to be collected that are recognized over the remaining life of the security	0	0
Reductions for securities sold during the period	(80,000)	(482,000)
Balance at end of period	$ 61,956,000	$ 67,086,000