Investments (Details Textuals) (USD $)	3 Months Ended
	Mar. 31, 2013
Investment [Abstract]
Condition for categorizing the impaired securities	$ 500,000
Condition for categorizing the impaired securities, percentage	10.00%
Gross unrealized losses on fixed income securities	$ 17,800,000
Weighted-average life of mortgage-backed and asset-backed securities, Years	5.9