Common Stock and Share-Based Compensation - Summary of Phantom Share Activity (Detail) - Phantom shares	6 Months Ended
	Jun. 30, 2017 $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years
Shares
Outstanding at beginning balance (in shares) | shares	1,361,062
Granted (in shares) | shares	767,521
Converted/paid (in shares) | shares	(600,346)
Forfeited (in shares) | shares	(140,783)
Outstanding at ending balance (in shares) | shares	1,387,454
Weighted Average Grant Date Fair Value
Outstanding at beginning balance, weighted average grant date fair value (in dollars per share) | $ / shares	$ 17.78
Weighted average grant date fair value, Granted (in dollars per share) | $ / shares	18.47
Weighted average grant date fair value, Converted/paid (in dollars per share) | $ / shares	17.00
Weighted average grant date fair value, Forfeited (in dollars per share) | $ / shares	18.27
Outstanding at ending balance, weighted average grant date fair value (in dollars per share) | $ / shares	$ 18.45