Goodwill and Intangible Assets (Narrative) (Detail) - USD ($)		3 Months Ended								12 Months Ended
	Oct. 01, 2020	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets [Line Items]
Impairment of goodwill	$ 0					$ 0	$ 0	$ 224,272,000	$ 0	$ 0	$ 224,272,000	$ 0
Impairment of intangible asset						0	0	17,308,000	0	0	17,308,000	0
Amortization of intangible assets		$ 6,705,000	$ 6,750,000	$ 6,846,000	$ 6,918,000	6,925,000	$ 6,970,000	$ 8,076,000	$ 8,105,000	27,219,000	30,076,000	$ 32,864,000
United States
Finite-Lived Intangible Assets [Line Items]
Long-lived intangible assets, net		$ 52,300,000				$ 79,500,000				$ 52,300,000	$ 79,500,000