Income Taxes (Tax Effects of Temporary Differences That Give Rise to Significant Portions of Deferred Tax Assets and Liabilities) (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Noncurrent deferred tax assets:
Accounts receivable	$ 948	$ 1,422
Advertising relationships	954	2,548
Other liabilities	20,486	27,014
Debt costs	6,987	0
Tax credits	2,249	2,042
Net operating loss	75,832	111,778
Noncurrent deferred tax assets	107,456	144,804
Less: valuation allowance	(75,460)	(17,205)
Net noncurrent deferred tax assets	31,996	127,599
Noncurrent deferred tax liabilities:
Intangible assets	242,822	482,620
Property and equipment	8,417	20,485
Cancellation of debt income	0	12,544
Other	7	0
Noncurrent deferred tax liabilities	251,246	515,649
Net noncurrent deferred tax liabilities	219,250
Net noncurrent deferred tax liabilities	0	388,050
Net deferred tax liabilities	$ 219,250	$ 388,050