Nature of Business (Details) (USD $)	Dec. 31, 2013
Nature of Business [Abstract]
Direct domestic primary insurance in force	$ 158,700,000,000
Direct domestic primary risk in force	41,100,000,000
Direct pool risk in force	1,000,000,000
Direct pool risk in force on pool policies with aggregate loss limits	400,000,000
Direct pool risk in force on pool policies with no aggregate loss limits	600,000,000
Risk in force in Australia	$ 480,000,000
Coverage percentage on insurance in force in Australia (in hundredths)	100.00%