Income Taxes - Component of Income Taxes (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Disclosure [Abstract]
Expected tax expense (benefit), at U.S. federal statutory income tax rate of 35%	$ 12,100,000	$ (33,800,000)	$ 27,000,000
Incremental U.S. tax and rate differences on equity in earnings	(7,400,000)	(7,400,000)	(7,400,000)
Nondeductible goodwill impairment			2,200,000
U.S. state income taxes and other, net	300,000	(700,000)	(1,900,000)
Income tax expense (benefit)	$ 5,003,000	$ (41,911,000)	$ 19,933,000