Share-Based Compensation - Schedule of Information with Respect to all Outstanding Restricted Stock (Detail) - Restricted Stock Units [Member] shares in Thousands	9 Months Ended
	Sep. 30, 2019 $ / shares shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Beginning balance of Outstanding, Units | shares	2,017	[1]
Granted, Units | shares	428
Vested, Units | shares	(493)
Forfeited, Units | shares	(23)
Ending balance of Outstanding, Units | shares	1,929
Beginning balance of Outstanding, Weighted Average Grant-Date Fair Value Per Unit | $ / shares	$ 12.70	[1]
Granted, Weighted Average Grant-Date Fair Value Per Unit | $ / shares	21.31
Vested, Weighted Average Grant-Date Fair Value Per Unit | $ / shares	6.11
Forfeited, Weighted Average Grant-Date Fair Value Per Unit | $ / shares	11.42
Ending balance of Outstanding, Weighted Average Grant-Date Fair Value Per Unit | $ / shares	$ 16.31

[1] The weighted average grant-date fair value per unit as of December 31, 2018 reflects an adjusted fair value per unit from $10.59 to $12.70 due to the modification of grants approved by the Board of Directors during the current quarter for our performance-based grants granted on December 14, 2018.