Components of Selected Balance Sheet Accounts (Additional Information) (Detail) $ in Millions	Dec. 31, 2014 USD ($)
Performance Based Restricted Stock Units (PBRSUs)
Compensation-related obligations [Line Items]
Liability-classifed share-based compensation awards, noncurrent	$ 6.4

Aggregate carrying value as of the balance sheet date of the liabilities for stock option plans and other equity-based compensation arrangements payable after one year (or the operating cycle, if longer).

No definition available.

Name:	us-gaap_DeferredCompensationSharebasedArrangementsLiabilityClassifiedNoncurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant