Related Party Transactions - Additional Information (Detail) (Consulting Services [Member], USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Related Party One [Member]
Related Party Transaction [Line Items]
Rent and other expenses paid	$ 0.4	$ 0.4	$ 0.4
Related Party Two [Member]
Related Party Transaction [Line Items]
Rent and other expenses paid	$ 0.1	$ 0.3	$ 0.1

Amount of selling, general and administrative expenses resulting from transactions, excluding transactions that are eliminated in consolidated or combined financial statements, with related party.

No definition available.

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