Share-Based Employee Compensation - Shares Authorized, Available for Future Grant and Outstanding Under Each Plans (Detail)	Dec. 31, 2016 shares
Equity Incentive Plan [Line Items]
Authorized (in shares)	25,000,000
Available (in shares)	5,040,000
Outstanding (in shares)	4,791,000
2004 Plan
Equity Incentive Plan [Line Items]
Authorized (in shares)	24,000,000
Available (in shares)	4,232,000
Outstanding (in shares)	4,747,000
2013 Directors Plan
Equity Incentive Plan [Line Items]
Authorized (in shares)	1,000,000
Available (in shares)	808,000
Outstanding (in shares)	44,000