Goodwill and Intangible Assets - Company's Purchased Intangible Assets (Detail) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Intangibles	$ 289,282	$ 295,805
Accumulated Amortization	(137,745)	(137,385)
Net Intangibles	$ 151,537	$ 158,420
Weighted Average Amortization Period (years)	5 years	5 years
Customer Relationships [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Intangibles	$ 188,083	$ 191,171
Accumulated Amortization	(122,624)	(121,074)
Net Intangibles	$ 65,459	$ 70,097
Weighted Average Amortization Period (years)	10 years	10 years
Trade Name and Trademarks [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Intangibles	$ 19,133	$ 19,380
Accumulated Amortization	(13,467)	(12,929)
Net Intangibles	$ 5,666	$ 6,451
Weighted Average Amortization Period (years)	8 years	8 years
Non-Compete Agreements [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Intangibles	$ 902	$ 2,769
Accumulated Amortization	(427)	(2,181)
Net Intangibles	$ 475	$ 588
Weighted Average Amortization Period (years)	3 years	3 years
Content Library [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Intangibles	$ 497	$ 506
Accumulated Amortization	$ (497)	$ (506)
Weighted Average Amortization Period (years)	2 years	2 years
Proprietary Software [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Intangibles	$ 870	$ 870
Accumulated Amortization	(730)	(695)
Net Intangibles	$ 140	$ 175
Weighted Average Amortization Period (years)	5 years	5 years
Domain Names Not Subject To Amortization [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Intangibles	$ 79,797	$ 81,109
Net Intangibles	$ 79,797	$ 81,109