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Fair Value Measurements - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Transfers of assets from level 1 to 2	$ 29,800,000	$ 0	$ 0
Transfers of assets from level 2 to 1		0	0
Transfers of assets into level 3		0	0
Transfers of assets out of level 3		0	0
Transfers of liabilities from level 1 to 2	0	0	0
Transfers of liabilities from level 2 to 1	0	0	0
Transfers of liabilities into level 3	0	0	0
Transfers of liabilities out of level 3	0	0	$ 0
Lease obligations [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Liabilities fair value disclosure	$ 1,544,000	98,105,000
Lease obligations [Member] | Building [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Liabilities fair value disclosure		$ 96,200,000

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