Income taxes - components of provision for income taxes from continuing operations (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current:
Federal	$ 133,621	$ 2,344	$ (4,700)
State	5,213	5,230	2,377
Foreign	35,444	28,842	53,151
Deferred:
Federal	(258,247)	(25,141)	(35,750)
State	1,459	(1,837)	(5,012)
Foreign	212,158	(1,364)	(2,228)
Provision for income taxes from continuing operations	$ 129,648	$ 8,074	$ 7,838