Summary Quarterly Consolidated Financial Information (Parenthetical) (Detail) - USD ($)	3 Months Ended		12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Quarterly Financial Information [Line Items]
Impairments of goodwill			$ 51,200,000	$ 0	$ 0
Impairment of indefinite-lived tradenames					0
Acquisition costs related to the cash settlement of stock-based award held by transferring employees	$ 61,500,000
Foreign currency remeasurement gain (loss)			(9,757,000)	$ 13,982,000	$ (20,761,000)
Sales
Quarterly Financial Information [Line Items]
Reduction (increase) to net sales	(8,100,000)	$ 16,400,000
(Gain)/loss on foreign currency
Quarterly Financial Information [Line Items]
Correction of an immaterial misstatement from changes in exchange rates		8,000,000
Pace Plc
Quarterly Financial Information [Line Items]
Foreign currency remeasurement gain (loss)		$ 16,000,000
Cloud Tv Reporting Unit
Quarterly Financial Information [Line Items]
Impairments of goodwill	51,200,000		51,200,000
Cloud Tv Reporting Unit | Trade Names [Member]
Quarterly Financial Information [Line Items]
Impairment of indefinite-lived tradenames	3,800,000		3,800,000
UNITED KINGDOM
Quarterly Financial Information [Line Items]
Foreign currency remeasurement gain (loss)			(10,500,000)
Non-controlling Interest | Cloud Tv Reporting Unit
Quarterly Financial Information [Line Items]
Impairments of goodwill	17,900,000		$ 17,900,000
Impairment loss attributable to non controlling interest	19,300,000
Non-controlling Interest | Cloud Tv Reporting Unit | Trade Names [Member]
Quarterly Financial Information [Line Items]
Impairment of indefinite-lived tradenames	$ 1,300,000