Stockholders' Equity - Summary of Stock Option Activity (Detail) - Non Qualified Stock Option [Member] $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2020 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares, Options Beginning Balance | shares	9.6
Shares, Exercised | shares	(0.1)
Shares, Forfeited | shares	(0.1)
Shares, Options Ending Balance | shares	9.4
Shares, Options vested Ending Balance | shares	4.0
Shares, Options unvested Ending Balance | shares	5.4
Weighted Average Option Exercise Price Per Share, Options Beginning Balance | $ / shares	$ 17.70
Weighted Average Option Exercise Price Per Share, Exercised | $ / shares	8.50
Weighted Average Option Exercise Price Per Share, Forfeited | $ / shares	18.60
Weighted Average Option Exercise Price Per Share, Options Ending Balance | $ / shares	17.71
Weighted Average Option Exercise Price Per Share, Options vested Ending Balance | $ / shares	16.10
Weighted Average Option Exercise Price Per Share, Options unvested Ending Balance | $ / shares	$ 18.92
Weighted Average Remaining Contractual Term in Years, Options outstanding	6 years 9 months 18 days
Weighted Average Remaining Contractual Term in Years, Options vested	3 years 9 months 18 days
Weighted Average Remaining Contractual Term in Years, Options unvested	9 years 1 month 6 days
Aggregate Intrinsic Value, Options outstanding as of March 31, 2020 | $	$ 7.2
Aggregate Intrinsic Value, Options vested as of March 31, 2020 | $	$ 7.2