Summary of Significant Accounting Policies - Significant Estimates Used by Management in Determining Fair Values of Company's Reporting Units (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Goodwill [Line Items]
Years of cash flows before terminal value	5 years	5 years	5 years
Discounted cash flows	100.00%	70.00%	70.00%
Market multiple	0.00%	15.00%	15.00%
Market capitalization	0.00%	15.00%	15.00%
Weighted Average Cost of Capital
Goodwill [Line Items]
Measurement input		0.125
Weighted Average Cost of Capital | Minimum
Goodwill [Line Items]
Measurement input	0.125		0.120
Weighted Average Cost of Capital | Maximum
Goodwill [Line Items]
Measurement input	0.135		0.150
Transaction Multiples Applied to EBITDA
Goodwill [Line Items]
Measurement input		6
Transaction Multiples Applied to EBITDA | Minimum
Goodwill [Line Items]
Measurement input	6.0		6.5
Transaction Multiples Applied to EBITDA | Maximum
Goodwill [Line Items]
Measurement input	9.0		9.0
Guideline Public Company Multiples Applied to EBITDA
Goodwill [Line Items]
Measurement input		6.5
Guideline Public Company Multiples Applied to EBITDA | Minimum
Goodwill [Line Items]
Measurement input			6.5
Guideline Public Company Multiples Applied to EBITDA | Maximum
Goodwill [Line Items]
Measurement input			9.5
Compounded Revenue Growth Rates
Goodwill [Line Items]
Measurement input		(0.09)
Compounded Revenue Growth Rates | Minimum
Goodwill [Line Items]
Measurement input	(0.08)		(0.14)
Compounded Revenue Growth Rates | Maximum
Goodwill [Line Items]
Measurement input	0.26		0.08