Related Party Transactions - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Related Party Transactions [Abstract]
Lease agreement terms	5 years
Related party lease expenses	$ 8.7us-gaap_CostsAndExpensesRelatedParty	$ 4.6us-gaap_CostsAndExpensesRelatedParty	$ 4.2us-gaap_CostsAndExpensesRelatedParty

Costs of sales and operating expenses for the period incurred from transactions with related parties.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.2)

-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

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