Investments (Investment Gains and Losses) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Held to maturity debt securities:
Real estate gains (losses)	$ 0	$ 0
Mortgage loans write-downs	0	0
Other	0	0
Totals	2,374	1,366
Percentage of gains on bonds, due to calls of securities	15.50%
Total other-than-temporary impairment gains (losses) on debt securities	382	(253)
Portion of loss (gain) recognized in comprehensive income	(443)	78
Net impairment losses (gains) on debt securities recognized in earnings	(61)	(175)
Equity securities impairments	0	(24)
Net OTTI losses recognized in earnings	(61)	(199)
Non-Credit Other-than-Temporary Impairment, Credit Losses Recognized in Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance, cumulative credit losses related to other-than-temporary impairments	2,247	1,122	1,122
Reductions for securities sold during current period	0		(118)
Additions for credit losses not previously recognized in other-than-temporary impairments	61		1,243
Ending balance, cumulative credit losses related to other-than-temporary impairments	2,308		2,247
Debt Securities [Member]
Held to maturity debt securities:
Realized gains on disposal	329	116
Realized losses on disposal	(69)	(374)
Debt Securities [Member]
Available for sale debt securities:
Realized gains on disposal	1,796	1,628
Realized losses on disposal	0	0
Equity Securities [Member]
Held to maturity debt securities:
Equity securities realized gains (losses)	$ 318	$ (4)

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