Income Taxes - Component of Income Taxes (Detail) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Income Tax Disclosure [Line Items]
Expected tax expense (benefit) at U.S. federal statutory income tax rate of 35%	$ 1,900,000	$ (7,700,000)	$ 3,700,000	$ (12,800,000)
Incremental U.S. tax and rate differences on equity in earnings	(2,300,000)		(3,300,000)	(7,400,000)
Nontaxable income		(500,000)	(300,000)	(700,000)
U.S. state income taxes and other, net	300,000	200,000	700,000	200,000
Total	$ (125,000)	$ (8,024,000)	$ 845,000	$ (20,682,000)