Commitments and Contingencies - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Loss Contingencies [Line Items]
Line of credit, performance and payment bonds	$ 193.4	$ 35.8
Operating Partnership [Member]
Loss Contingencies [Line Items]
Outstanding letters of credit	$ 11.0	$ 3.0

Amount of contractual obligation, including but not limited to, long-term debt, capital lease obligations, operating lease obligations, purchase obligations, and other commitments.

No definition available.

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