Income Taxes - Deferred Tax Balance Classification in Balance Sheet (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Long term deferred tax assets	$ 3,152	$ 1,801
Long term deferred tax liabilities	(491,946)	(518,912)
Net deferred tax liabilities	$ (488,794)	$ (517,111)

Amount after allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards classified as noncurrent.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant