Share-Based Compensation - Schedule of Information with Respect to all Outstanding Restricted Stock (Parenthetical) (Detail) - Restricted Stock Units [Member] - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2019	Dec. 31, 2018		Dec. 31, 2016
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vested stock settled in cash	6,300
Weighted average grant-date adjusted fair value per unit	$ 5.32	$ 16.34	$ 12.70	[1]	$ 4.63
Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted average grant-date adjusted fair value per unit			10.59
Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted average grant-date adjusted fair value per unit			$ 12.70

[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 year for our performance-based awards granted on December 14, 2018.