Stock-Based Compensation - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Software and Capitalized Software Costs [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Capitalized compensation cost	$ 1.6	$ 3.3
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Compensation expense related to ESPP	15.8	$ 31.1
Total unrecognized compensation cost related to unvested restricted stock	$ 143.0
Unrecognized compensation expected for unvested shares to be recognized	1 year 10 months 24 days
Restricted Stock [Member] \| Market-Based Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Number of shares vested	360,948
Restricted Stock [Member] \| Time-Based Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Number of shares vested	85,148
Restricted Stock [Member] \| LTIP [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Restricted shares of common stock issued	446,096
Restricted Stock [Member] \| Executive Officers [Member] \| Vest 50% on the first date, if any, that the Company’s TEV (calculated as defined in the applicable restricted stock award agreement) equals or exceeds $23.75 billion [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Market-based vesting percentage, restricted shares	50.00%
Total enterprise value	$ 23,750.0
Restricted Stock [Member] \| Executive Officers [Member] \| Vest 50% on the first date, if any, that the Company’s TEV equals or exceeds $27.7 billion [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Market-based vesting percentage, restricted shares	50.00%
Total enterprise value	$ 27,700.0
Restricted Stock [Member] \| Non Executive Employees [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share-based compensation arrangement by share-based payment award, award vesting rights	over periods ranging from three to four years
Restricted Stock [Member] \| Non Executive Employees [Member] \| Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	3 years
Restricted Stock [Member] \| Non Executive Employees [Member] \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	4 years
Restricted Stock [Member] \| Non Executive Employees [Member] \| Vest 50% on the first date, if any, that the Company’s TEV equals or exceeds $19.8 billion [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Market-based vesting percentage, restricted shares	50.00%
Total enterprise value	$ 19,800.0
Restricted Stock [Member] \| Non Executive Employees [Member] \| Vest 50% on the first date, if any, that the Company’s TEV equals or exceeds $22.15 billion [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Market-based vesting percentage, restricted shares	50.00%
Total enterprise value	$ 22,150.0

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