Annual report pursuant to Section 13 and 15(d)

Financial Performance Factors and Respective Vesting (Detail)

v3.6.0.2
Financial Performance Factors and Respective Vesting (Detail) - Restricted Stock Units (RSUs)
12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Threshold IRR 6.00% 7.50% 8.50%
Target IRR 8.00% 9.50% 10.50%
Maximum IRR 10.00% 11.50% 12.50%
Threshold IRR      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Percentage of Shares Vesting 33.30%    
Targeted IRR      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Percentage of Shares Vesting 66.60%    
Maximum IRR      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Percentage of Shares Vesting 100.00%