Commitments and Contingencies - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
Construction costs related to development and expansion	$ 10.1
Operating and capital leases expenses	$ 0.2	$ 0.3

The minimum amount the entity agreed to spend under the long-term purchase commitment.

No definition available.

Name:	us-gaap_LongTermPurchaseCommitmentAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration