Fair Value Measurements - Estimated Fair Values of Assets Measured on Nonrecurring Basis (Parenthetical) (Detail) - Fair Value, Nonrecurring [Member] - Fair Value, Inputs, Level 3 [Member]	12 Months Ended
	Dec. 31, 2020
Measurement Input, Long-term Revenue Growth Rate [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement input	3
Minimum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discounted cash flow term	1 year 8 months 12 days
Terminal capitalization rate	7.25%
Minimum [Member] | Discount Rate [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement input	9.5
Maximum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discounted cash flow term	10 years
Terminal capitalization rate	7.75%
Maximum [Member] | Discount Rate [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement input	12.5