Income Taxes - Component of Income Taxes (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Income Tax Disclosure [Abstract]
Expected tax expense (benefit), at U.S. federal statutory income tax rate of 35%	$ (800)	$ 6,300	$ (15,000)	$ 10,000
Rate differences on equity in earnings (losses) of Kronos	(2,700)	(2,500)	(7,400)	(5,800)
Adjustment to the reserve for uncertain tax positions, net			(3,000)
Nontaxable income	(100)	200	(300)	(100)
U.S. state income taxes and other, net	100	(200)	200	500
Total	$ (3,581)	$ 3,800	$ (25,534)	$ 4,645