Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018	Jan. 01, 2019
Minimum
Schedule Of Significant Accounting Policies [Line Items]
Additional terms of renewal option	1 year		1 year
Additional terms of termination option			1 year
Maximum
Schedule Of Significant Accounting Policies [Line Items]
Additional terms of renewal option	5 years		5 years
Additional terms of termination option			5 years
Topic 842
Schedule Of Significant Accounting Policies [Line Items]
Additional lease liabilities						$ 328,978
Additional right of use assets						$ 309,687
General Electric Company | Credit Concentration Risk | Receivables
Schedule Of Significant Accounting Policies [Line Items]
Concentration risk, percentage			16.00%		11.00%
General Electric Company | Credit Concentration Risk | Revenue From Contract With Customer
Schedule Of Significant Accounting Policies [Line Items]
Concentration risk, percentage	14.00%	9.00%	14.00%	9.00%