XML 58 R45.htm IDEA: XBRL DOCUMENT v3.4.0.3
Equity - Summary of Fair Value of Value Sharing Equity Program Grants (Detail) - 2016 VSEP [Member]
3 Months Ended
Mar. 31, 2016
Fair Value Inputs Equity Quantitative Information [Line Items]  
Risk-free interest rate 0.80%
Weighted-average dividend yield 5.00%
Expected life 3 years
Minimum [Member]  
Fair Value Inputs Equity Quantitative Information [Line Items]  
Expected volatility 17.00%
Maximum [Member]  
Fair Value Inputs Equity Quantitative Information [Line Items]  
Expected volatility 19.00%