Restricted Stock Unit Activity (Detail)	12 Months Ended
	Dec. 31, 2019 $ / shares shares
Time Based Restricted Stock Units
Shares
Outstanding at beginning of year	2,602,608
Granted	1,505,048
Vested	(1,135,231)	[1]
Forfeited	(340,699)
Outstanding at end of year	2,631,726
Performance Based Restricted Stock Units
Shares
Outstanding at beginning of year	435,315
Vested	(38,000)	[1]
Outstanding at end of year	397,315
Restricted Stock Units (RSUs)
Weighted Average Grant Date Fair Value Per Share
Outstanding at beginning of year | $ / shares	$ 18.95
Granted | $ / shares	12.40
Vested | $ / shares	19.19	[1]
Forfeited | $ / shares	17.08
Outstanding at end of year | $ / shares	$ 15.81

[1] ^{All of the performance-based restricted stock units that vested during 2019 were granted in 2017.}