Revenue from Contracts with Customers - Additional Information (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($) Revenue_Stream	Jan. 01, 2018 USD ($)	Dec. 31, 2017 USD ($)
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Number of primary revenue streams | Revenue_Stream	2
Deferred costs for fulfilment of contract	$ 20,805		$ 0
Total backlog	$ 3,900,000
Total backlog, percentage, year one	39.00%
Total backlog, percentage after year one	61.00%
Selling, General and Administrative Expenses [Member]
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Capitalized Contract Cost Amortization	$ 29,700
Prepaid Expenses and Other Current Assets [Member]
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Capitalized Contract Cost, Gross	24,700
Other Assets [Member]
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Capitalized Contract Cost, Gross	$ 33,800
ASC 606
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Deferred costs for fulfilment of contract		$ 5,500
ASC 606 | Minimum [Member]
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Capitalized cost, amortization period	2 years
ASC 606 | Maximum [Member]
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Capitalized cost, amortization period	6 years