Shared-Based Compensation - Reconciliation of Restricted Stock Option Activity (Detail)	9 Months Ended
	Sep. 30, 2019 $ / shares shares
Restricted Stock
Nonvested Shares (in thousands)
Nonvested restricted shares, beginning balance (in shares) | shares	146,000
Nonvested restricted shares, granted (in shares) | shares	309,234
Nonvested restricted shares, vested (in shares) | shares	(144,000)
Nonvested restricted shares, forfeited (in shares) | shares	(79,000)
Nonvested restricted shares, ending balance (in shares) | shares	232,000
Weighted average grant-date fair value, beginning balance (in dollara per share) | $ / shares	$ 22.07
Weighted average grant-date fair value, granted (in dollars per share) | $ / shares	7.85
Weighted average grant-date fair value, vested (in dollars per share) | $ / shares	18.14
Weighted average grant-date fair value, forfeited (in dollars per share) | $ / shares	10.09
Weighted average grant-date fair value, ending balance (in dollars per share) | $ / shares	$ 9.62
TSR Awards
Nonvested Shares (in thousands)
Nonvested restricted shares, beginning balance (in shares) | shares	94,000
Nonvested restricted shares, granted (in shares) | shares	136,000
Nonvested restricted shares, forfeited (in shares) | shares	(139,000)
Nonvested restricted shares, ending balance (in shares) | shares	91,000
Weighted average grant-date fair value, beginning balance (in dollara per share) | $ / shares	$ 26.84
Weighted average grant-date fair value, granted (in dollars per share) | $ / shares	9.28
Weighted average grant-date fair value, forfeited (in dollars per share) | $ / shares	16.76
Weighted average grant-date fair value, ending balance (in dollars per share) | $ / shares	$ 16.03
ROIC Awards
Nonvested Shares (in thousands)
Nonvested restricted shares, beginning balance (in shares) | shares	100,000
Nonvested restricted shares, granted (in shares) | shares	174,000
Nonvested restricted shares, forfeited (in shares) | shares	(164,000)
Nonvested restricted shares, ending balance (in shares) | shares	110,000
Weighted average grant-date fair value, beginning balance (in dollara per share) | $ / shares	$ 24.39
Weighted average grant-date fair value, granted (in dollars per share) | $ / shares	7.93
Weighted average grant-date fair value, forfeited (in dollars per share) | $ / shares	14.20
Weighted average grant-date fair value, ending balance (in dollars per share) | $ / shares	$ 13.53