Fair Value Measurements - Financial Assets and Liabilities Measured on Recurring Basis (Detail) - USD ($) $ in Millions		Mar. 31, 2021	Mar. 05, 2021	Dec. 31, 2020
Warrant
Assets:
Asset			$ 5
Fair Value, Measurements, Recurring
Assets:
Asset		$ 30		$ 26
Liabilities:
Liabilities		67		76
Fair Value, Measurements, Recurring | Interest Rate Swap Arrangements
Liabilities:
Liabilities	[1]	44		52
Fair Value, Measurements, Recurring | Deferred Compensation Liabilities
Liabilities:
Liabilities	[2]	23		24
Fair Value, Measurements, Recurring | Plan Assets for Deferred Compensation
Assets:
Asset	[3]	23		24
Fair Value, Measurements, Recurring | Investment in Mutual Funds
Assets:
Asset	[4]	2		2
Fair Value, Measurements, Recurring | Warrant
Assets:
Asset	[5]	5
Fair Value, Measurements, Recurring | Level 1
Assets:
Asset		25		26
Liabilities:
Liabilities		23		24
Fair Value, Measurements, Recurring | Level 1 | Deferred Compensation Liabilities
Liabilities:
Liabilities	[2]	23		24
Fair Value, Measurements, Recurring | Level 1 | Plan Assets for Deferred Compensation
Assets:
Asset	[3]	23		24
Fair Value, Measurements, Recurring | Level 1 | Investment in Mutual Funds
Assets:
Asset	[4]	2		2
Fair Value, Measurements, Recurring | Level 2
Liabilities:
Liabilities		44		52
Fair Value, Measurements, Recurring | Level 2 | Interest Rate Swap Arrangements
Liabilities:
Liabilities	[1]	44		$ 52
Fair Value, Measurements, Recurring | Level 3
Assets:
Asset		5
Fair Value, Measurements, Recurring | Level 3 | Warrant
Assets:
Asset	[5]	$ 5

[1] Derivative financial instruments include interest rate swap arrangements recorded at fair value based on externally-developed valuation models that use readily observable market parameters and the consideration of counterparty risk.

[2] The Company offers certain employees the opportunity to participate in a deferred compensation plan. A participant’s deferrals are invested in a variety of participant directed stock and bond mutual funds and are classified as equity securities. Changes in the fair value of these securities are measured using quoted prices in active markets based on the market price per unit multiplied by the number of units held exclusive of any transaction costs. A corresponding adjustment for changes in fair value of the equity securities is also reflected in the changes in fair value of the deferred compensation obligation.

[3] Plan assets are comprised of investments in mutual funds, which are intended to fund liabilities arising from deferred compensation plans. These investments are carried at fair value, which is based on quoted market prices at period end in active markets. These investments are classified as equity securities with any gains or losses resulting from changes in fair value recorded in other income/(expense), net in the condensed consolidated statement of operations.

[4] Investments in mutual funds are money-market accounts held with the intention of funding certain specific retirement plans.

[5] The estimated fair value of the Connect Warrant issued March 5, 2021, of $5 million which was part of the proceeds related to the sale was included in the net gain on sale of the Global Connect segment. The Connect Warrant is marked-to-market each reporting period with the subsequent change in fair value recorded to other income/(expense), net in the condensed consolidated statement of operations.  The Connect Warrant is reported within other non-current assets within the condensed consolidated balance sheet.  The fair value of the Connect Warrant asset is estimated using a Black-Scholes option-pricing model.