Summarized Activity in Liability for Unpaid Losses and Loss Adjustment Expenses (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Liability for Claims and Claims Adjustment Expense [Line Items]
Balance at beginning of period	$ 779,466	$ 879,114	$ 971,377
Ceded reinsurance receivables	192,491	240,566	283,652
Net balance at beginning of period	586,975	638,548	687,725
Incurred losses and loss adjustment expenses related to:
Current year	153,994	140,873	149,183
Prior years	(16,433)	(7,882)	4,445
Total incurred losses and loss adjustment expenses	137,561	132,991	153,628
Paid losses and loss adjustment expenses related to:
Current year	55,485	50,732	52,164
Prior years	116,780	133,832	150,641
Total paid losses and loss adjustment expenses	172,265	184,564	202,805
Net balance at end of period	552,271	586,975	638,548
Ceded reinsurance receivables	123,201	192,491	240,566
Balance at end of period	$ 675,472	$ 779,466	$ 879,114