Investments - Quantitative Information about Level 3 Fair Value Measurements (Detail) (USD $) In Thousands, unless otherwise specified					12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2013 Fair Value, Inputs, Level 3 [Member]	Dec. 31, 2013 Fair Value, Inputs, Level 3 [Member] Other Investments [Member] Third-party Pricing Without Adjustment [Member]	Dec. 31, 2013 Fair Value, Inputs, Level 3 [Member] Collateralized Debt Obligations [Member] Discounted Cash Flows Valuation Technique [Member]	Dec. 31, 2013 Fair Value, Inputs, Level 3 [Member] Private Placement Bonds [Member] Discounted Cash Flows Valuation Technique [Member]	Dec. 31, 2013 Weighted Average [Member] Fair Value, Inputs, Level 3 [Member] Collateralized Debt Obligations [Member] Discounted Cash Flows Valuation Technique [Member]	Dec. 31, 2013 Weighted Average [Member] Fair Value, Inputs, Level 3 [Member] Private Placement Bonds [Member] Discounted Cash Flows Valuation Technique [Member]
Quantitative Information About Significant Unobservable Inputs [Line Items]
Fair value fixed maturities measured on recurring basis	$ 12,879,133	$ 13,541,193	$ 359,281	$ 776	$ 58,205	$ 300,300
Discount rate					15.00%		15.00%
Credit rating						BBB- to A+		BBB