Quarterly report pursuant to Section 13 or 15(d)

Share-Based Payments - Assumptions used in Estimating Fair Value (Details)

v3.8.0.1
Share-Based Payments - Assumptions used in Estimating Fair Value (Details) - All Plans - Restricted Stock
3 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Expected volatility (as a percent) 20.50% 20.20%
Dividend yield (as a percent) 1.00% 1.10%
Average risk-free interest rate (as a percent) 2.00% 1.70%
Average expected term (years) 2 years 30 days 2 years 29 days