Premiums Receivable - Summarizes the Activity in the Allowance for Doubtful Accounts (Parenthetical) (Detail) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Receivables [Line Items]
Provision for bad debts	$ 806	$ 673	$ 52
One-Time Adjustment [Member]
Receivables [Line Items]
Provision for bad debts			$ 1,700

Amount of expense for known and estimated loss on collection of premiums receivable.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 4
-Subparagraph (SX 210.12-09)
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e24092-122690

Name:	us-gaap_PremiumsReceivableAllowanceForDoubtfulAccountsProvisionChargedToExpense1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration