Share-Based Compensation Plan (Details) - USD ($) $ / shares in Units, $ in Millions | Feb. 15, 2017 | Feb. 10, 2016 | Jul. 27, 2015 | Feb. 11, 2015 | Feb. 04, 2014 | Dec. 13, 2013 | Jan. 30, 2013 | Mar. 31, 2017 |
Restricted Stock [Member] | | | | | | | | |
Summary of restricted share activity | | | | | | | | |
Unvested shares, Beginning balance | | | | | | | | 135,891 |
Unvested shares, Granted | | | | | | | | 58,539 |
Vested, shares | | | | | | | | (57,559) |
Forfeited, shares | | | | | | | | (200) |
Unvested shares, Ending balance | | | | | | | | 136,671 |
Unvested weighted average grant date fair value, beginning balance (in usd per share) | | | | | | | | $ 30.82 |
Granted, weighted average grant date fair value (in usd per share) | | | | | | | | 29.64 |
Vested, weighted average grant date fair value (in usd per share) | | | | | | | | 31.50 |
Forfeited, weighted average grant date fair value (in usd per share) | | | | | | | | 26.97 |
Unvested weighted average grant date fair value, ending balance (in usd per share) | | | | | | | | $ 30.03 |
Performance Shares [Member] | January 2013 [Member] | | | | | | | | |
Summary of restricted share activity | | | | | | | | |
Unvested shares, Granted | | | | | | | 72,118 | |
Performance Shares [Member] | January 2013 [Member] | Relative TSR [Member] | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract] | | | | | | | | |
Percentage of Total Award | | | | | | | 30.00% | |
Grant Date Fair Value by Component ($ in millions) | | | | | | | $ 0.7 | |
Volatility | | | | | | | 31.00% | |
Interest Rate | | | | | | | 0.41% | |
Dividend Yield | | | | | | | 2.20% | |
Performance Shares [Member] | January 2013 [Member] | Absolute TSR [Member] | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract] | | | | | | | | |
Percentage of Total Award | | | | | | | 30.00% | |
Grant Date Fair Value by Component ($ in millions) | | | | | | | $ 0.5 | |
Volatility | | | | | | | 31.00% | |
Interest Rate | | | | | | | 0.41% | |
Dividend Yield | | | | | | | 2.20% | |
Performance Shares [Member] | January 2013 [Member] | EBITDA Comparison [Member] | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract] | | | | | | | | |
Percentage of Total Award | | | | | | | 40.00% | |
Grant Date Fair Value by Component ($ in millions) | | | | | | | $ 0.7 | |
Volatility | | | | | | | 31.00% | |
Interest Rate | | | | | | | 0.41% | |
Dividend Yield | | | | | | | 2.20% | |
Performance Shares [Member] | December 2013 [Member] | | | | | | | | |
Summary of restricted share activity | | | | | | | | |
Unvested shares, Granted | | | | | | 252,088 | | |
Performance Shares [Member] | December 2013 [Member] | Relative TSR [Member] | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract] | | | | | | | | |
Percentage of Total Award | | | | | | 50.00% | | |
Grant Date Fair Value by Component ($ in millions) | | | | | | $ 4.7 | | |
Volatility | | | | | | 29.00% | | |
Dividend Yield | | | | | | 2.40% | | |
Performance Shares [Member] | December 2013 [Member] | Relative TSR [Member] | Minimum [Member] | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract] | | | | | | | | |
Interest Rate | | | | | | 0.34% | | |
Performance Shares [Member] | December 2013 [Member] | Relative TSR [Member] | Maximum [Member] | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract] | | | | | | | | |
Interest Rate | | | | | | 2.25% | | |
Performance Shares [Member] | December 2013 [Member] | Absolute TSR [Member] | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract] | | | | | | | | |
Percentage of Total Award | | | | | | 50.00% | | |
Grant Date Fair Value by Component ($ in millions) | | | | | | $ 2.9 | | |
Volatility | | | | | | 29.00% | | |
Dividend Yield | | | | | | 2.40% | | |
Performance Shares [Member] | December 2013 [Member] | Absolute TSR [Member] | Minimum [Member] | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract] | | | | | | | | |
Interest Rate | | | | | | 0.34% | | |
Performance Shares [Member] | December 2013 [Member] | Absolute TSR [Member] | Maximum [Member] | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract] | | | | | | | | |
Interest Rate | | | | | | 2.25% | | |
Performance Shares [Member] | February 2014 [Member] | | | | | | | | |
Summary of restricted share activity | | | | | | | | |
Unvested shares, Granted | | | | | 66,483 | | | |
Performance Shares [Member] | February 2014 [Member] | Relative TSR [Member] | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract] | | | | | | | | |
Percentage of Total Award | | | | | 30.00% | | | |
Grant Date Fair Value by Component ($ in millions) | | | | | $ 0.7 | | | |
Volatility | | | | | 29.00% | | | |
Interest Rate | | | | | 0.62% | | | |
Dividend Yield | | | | | 2.40% | | | |
Performance Shares [Member] | February 2014 [Member] | Absolute TSR [Member] | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract] | | | | | | | | |
Percentage of Total Award | | | | | 30.00% | | | |
Grant Date Fair Value by Component ($ in millions) | | | | | $ 0.5 | | | |
Volatility | | | | | 29.00% | | | |
Interest Rate | | | | | 0.62% | | | |
Dividend Yield | | | | | 2.40% | | | |
Performance Shares [Member] | February 2014 [Member] | EBITDA Comparison [Member] | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract] | | | | | | | | |
Percentage of Total Award | | | | | 40.00% | | | |
Grant Date Fair Value by Component ($ in millions) | | | | | $ 0.8 | | | |
Volatility | | | | | 29.00% | | | |
Interest Rate | | | | | 0.62% | | | |
Dividend Yield | | | | | 2.40% | | | |
Performance Shares [Member] | February 2015 [Member] | | | | | | | | |
Summary of restricted share activity | | | | | | | | |
Unvested shares, Granted | | | | 44,962 | | | | |
Performance Shares [Member] | February 2015 [Member] | Relative TSR [Member] | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract] | | | | | | | | |
Percentage of Total Award | | | | 30.00% | | | | |
Grant Date Fair Value by Component ($ in millions) | | | | $ 0.9 | | | | |
Volatility | | | | 22.00% | | | | |
Interest Rate | | | | 1.02% | | | | |
Dividend Yield | | | | 2.50% | | | | |
Performance Shares [Member] | February 2015 [Member] | Absolute TSR [Member] | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract] | | | | | | | | |
Percentage of Total Award | | | | 40.00% | | | | |
Grant Date Fair Value by Component ($ in millions) | | | | $ 0.7 | | | | |
Volatility | | | | 22.00% | | | | |
Interest Rate | | | | 1.02% | | | | |
Dividend Yield | | | | 2.50% | | | | |
Performance Shares [Member] | February 2015 [Member] | EBITDA Comparison [Member] | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract] | | | | | | | | |
Percentage of Total Award | | | | 30.00% | | | | |
Grant Date Fair Value by Component ($ in millions) | | | | $ 0.7 | | | | |
Volatility | | | | 22.00% | | | | |
Interest Rate | | | | 1.02% | | | | |
Dividend Yield | | | | 2.50% | | | | |
Performance Shares [Member] | July 2015 [Member] | | | | | | | | |
Summary of restricted share activity | | | | | | | | |
Unvested shares, Granted | | | 771 | | | | | |
Performance Shares [Member] | July 2015 [Member] | Relative TSR [Member] | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract] | | | | | | | | |
Percentage of Total Award | | | 30.00% | | | | | |
Grant Date Fair Value by Component ($ in millions) | | | $ 0 | | | | | |
Volatility | | | 22.00% | | | | | |
Interest Rate | | | 0.68% | | | | | |
Dividend Yield | | | 2.50% | | | | | |
Performance Shares [Member] | July 2015 [Member] | Absolute TSR [Member] | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract] | | | | | | | | |
Percentage of Total Award | | | 40.00% | | | | | |
Grant Date Fair Value by Component ($ in millions) | | | $ 0 | | | | | |
Volatility | | | 22.00% | | | | | |
Interest Rate | | | 0.68% | | | | | |
Dividend Yield | | | 2.50% | | | | | |
Performance Shares [Member] | July 2015 [Member] | EBITDA Comparison [Member] | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract] | | | | | | | | |
Percentage of Total Award | | | 30.00% | | | | | |
Grant Date Fair Value by Component ($ in millions) | | | $ 0 | | | | | |
Volatility | | | 22.00% | | | | | |
Interest Rate | | | 0.68% | | | | | |
Dividend Yield | | | 2.50% | | | | | |
Performance Shares [Member] | February 2016 [Member] | | | | | | | | |
Summary of restricted share activity | | | | | | | | |
Unvested shares, Granted | | 100,919 | | | | | | |
Performance Shares [Member] | February 2016 [Member] | Relative TSR [Member] | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract] | | | | | | | | |
Percentage of Total Award | | 70.00% | | | | | | |
Grant Date Fair Value by Component ($ in millions) | | $ 1.6 | | | | | | |
Volatility | | 25.00% | | | | | | |
Interest Rate | | 0.71% | | | | | | |
Dividend Yield | | 3.00% | | | | | | |
Performance Shares [Member] | February 2016 [Member] | Absolute TSR [Member] | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract] | | | | | | | | |
Percentage of Total Award | | 15.00% | | | | | | |
Grant Date Fair Value by Component ($ in millions) | | $ 0.2 | | | | | | |
Volatility | | 25.00% | | | | | | |
Interest Rate | | 0.71% | | | | | | |
Dividend Yield | | 3.00% | | | | | | |
Performance Shares [Member] | February 2016 [Member] | EBITDA Comparison [Member] | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract] | | | | | | | | |
Percentage of Total Award | | 15.00% | | | | | | |
Grant Date Fair Value by Component ($ in millions) | | $ 0.4 | | | | | | |
Volatility | | 25.00% | | | | | | |
Interest Rate | | 0.71% | | | | | | |
Dividend Yield | | 3.00% | | | | | | |
Performance Shares [Member] | February 2017 [Member] | | | | | | | | |
Summary of restricted share activity | | | | | | | | |
Unvested shares, Granted | 81,939 | | | | | | | |
Performance Shares [Member] | February 2017 [Member] | Relative TSR [Member] | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract] | | | | | | | | |
Percentage of Total Award | 65.00% | | | | | | | |
Volatility | 28.00% | | | | | | | |
Interest Rate | 1.27% | | | | | | | |
Dividend Yield | 5.60% | | | | | | | |
Performance Shares [Member] | February 2017 [Member] | Absolute TSR [Member] | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract] | | | | | | | | |
Percentage of Total Award | 35.00% | | | | | | | |
Volatility | 28.00% | | | | | | | |
Interest Rate | 1.27% | | | | | | | |
Dividend Yield | 5.60% | | | | | | | |
Performance Shares [Member] | February 2017 [Member] | Relative & Absolute TSR [Member] | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract] | | | | | | | | |
Grant Date Fair Value by Component ($ in millions) | $ 2.7 | | | | | | | |