Description of Business, Basis of Presentation and Significant Accounting Policies - Additional Information (Detail) - USD ($) shares in Millions		3 Months Ended								12 Months Ended
	Jan. 01, 2018	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Accumulated deficit		$ (1,143,000,000)				$ (823,000,000)				$ (1,143,000,000)	$ (823,000,000)
Increase in other assets		91,000,000				54,000,000				91,000,000	54,000,000	$ 17,000,000
Income tax expense (benefit)										7,000,000	(3,000,000)	125,000,000
Depreciation expense										104,000,000	67,000,000	$ 55,000,000
Impairment of long-lived assets										$ 0
Antidilutive options to purchase were excluded from computation of diluted earnings per share (in shares)										115.5		127.8
Operating (loss) income		$ (5,000,000)	$ 10,000,000	$ 10,000,000	$ (5,000,000)	$ 23,000,000	$ 14,000,000	$ 10,000,000	$ (4,000,000)	$ 10,000,000	43,000,000	$ 68,000,000
Other expenses										$ 9,000,000	$ 8,000,000	$ 6,000,000
Internal-Use Software
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Period capitalized on a straight-line basis when the asset is substantially ready for use										3 years
Minimum
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Contract term										1 month
Fees payment term (in days)										30 days
Maximum
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Contract term										5 years
Fees payment term (in days)										90 days
Equipment | Minimum
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives (in years)										3 years
Equipment | Maximum
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives (in years)										5 years
Building | Minimum
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives (in years)										25 years
Building | Maximum
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives (in years)										45 years
Employee Stock Option
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Antidilutive options to purchase were excluded from computation of diluted earnings per share (in shares)										2.0	2.6	2.7
Accounting Standards Update 2014-09
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Accumulated deficit	$ 19,000,000
Increase in other assets	17,000,000
Income tax expense (benefit)	10,000,000
Deferred Tax Liability | Accounting Standards Update 2014-09
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Accumulated deficit	26,000,000
Unbilled contract receivables	$ 20,000,000