Income Tax Expense Allocation (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Income tax expense	$ 23,935	$ 2,004	$ 7,671
Income from discontinued operations	0	0	(100)
Interest expense	(100)	200	(100)
Goodwill	0	(100)	0
Stockholders' equity	(7,200)	(2,100)	600
Total income tax expense	$ 16,600	$ 0	$ 8,100