Reinsurance - Schedule of Unsecured Reinsurance Recoverables from Reinsurers (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Ceded Credit Risk [Line Items]
Total reinsurance recoverables	$ 75,326	$ 101,352
Total unsecured reinsurance recoverables	35,993
Letters of credit and funds held [Member]
Ceded Credit Risk [Line Items]
Letters of credit and funds held	(39,333)
Ceded Credit Risk, Concentrated Credit Risk [Member] | Hannover Reinsurance (Ireland) Limited (A+) [Member]
Ceded Credit Risk [Line Items]
Total reinsurance recoverables	23,956
Ceded Credit Risk, Concentrated Credit Risk [Member] | Odyssey America Reinsurance Corporation (A) [Member]
Ceded Credit Risk [Line Items]
Total reinsurance recoverables	12,045
Ceded Credit Risk, Concentrated Credit Risk [Member] | Minnesota Workers' Compensation Reinsurance Association (NR) [Member]
Ceded Credit Risk [Line Items]
Total reinsurance recoverables	6,784
Ceded Credit Risk, Concentrated Credit Risk [Member] | Tokio Millenium Reinsurance Limited (A++) [Member]
Ceded Credit Risk [Line Items]
Total reinsurance recoverables	6,246
Ceded Credit Risk, Concentrated Credit Risk [Member] | Clearwater Insurance Company (bbb) [Member]
Ceded Credit Risk [Line Items]
Total reinsurance recoverables	5,693
Ceded Credit Risk, Concentrated Credit Risk [Member] | Other reinsurers [Member]
Ceded Credit Risk [Line Items]
Total reinsurance recoverables	$ 20,602