Investment in Joint Venture (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	May 31, 2008	Oct. 01, 2014
Schedule of Equity Method Investments [Line Items]
Investment in joint venture, at cost	$ 100,000,000	$ 100,000,000
Income (loss) from joint venture investme	19,883,000	35,701,000	73,510,000
Gulf Re
Schedule of Equity Method Investments [Line Items]
Investment in joint venture, at cost				100,000,000
Joint venture, ownership percentage				50.00%
Initial capital amount				200,000,000
Income (loss) from joint venture investme	14,100,000	400,000	1,100,000
Quota share agreement, percentage	90.00%
Gulf Re | Unearned premium reserves
Schedule of Equity Method Investments [Line Items]
Portfolio transfer amount					50,000,000
Gulf Re | Reserves for losses and loss expenses
Schedule of Equity Method Investments [Line Items]
Portfolio transfer amount					$ 65,000,000