Investments in Unconsolidated Affiliates - Combined Financial Information of Unconsolidated Affiliated Companies (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Assets:
Current assets	$ 41,212		$ 41,212
Noncurrent assets	151,903		151,903
Total assets	193,115		193,115
Liabilities:
Current liabilities	45,955		45,955
Noncurrent liabilities	71,914		71,914
Total liabilities	117,869		117,869
Results of operations:
Revenue	40,946	31,403	58,734	54,187
Net income loss	$ (1,145)	$ (5,328)	$ (10,498)	$ (13,697)