Share-Based Compensation Plan (Details) (USD $) In Millions, except Share data, unless otherwise specified	9 Months Ended	0 Months Ended
	Sep. 30, 2014 Restricted Stock [Member]	Feb. 08, 2012 February 2012 [Member] Performance Shares [Member]	Feb. 08, 2012 February 2012 [Member] Relative TSR [Member] Performance Shares [Member]		Feb. 08, 2012 February 2012 [Member] Absolute TSR [Member] Performance Shares [Member]		Feb. 08, 2012 February 2012 [Member] EBITDA Comparison [Member] Performance Shares [Member]		Jan. 30, 2013 January 2013 [Member] Performance Shares [Member]	Jan. 30, 2013 January 2013 [Member] Relative TSR [Member] Performance Shares [Member]		Jan. 30, 2013 January 2013 [Member] Absolute TSR [Member] Performance Shares [Member]		Jan. 30, 2013 January 2013 [Member] EBITDA Comparison [Member] Performance Shares [Member]		Dec. 13, 2013 December 2013 [Member] Performance Shares [Member]	Dec. 13, 2013 December 2013 [Member] Relative TSR [Member] Performance Shares [Member]		Dec. 13, 2013 December 2013 [Member] Absolute TSR [Member] Performance Shares [Member]		Feb. 04, 2014 February 2014 [Member] Performance Shares [Member]	Feb. 04, 2014 February 2014 [Member] Relative TSR [Member] Performance Shares [Member]		Feb. 04, 2014 February 2014 [Member] Absolute TSR [Member] Performance Shares [Member]		Feb. 04, 2014 February 2014 [Member] EBITDA Comparison [Member] Performance Shares [Member]		Dec. 13, 2013 Minimum [Member] December 2013 [Member] Relative TSR [Member] Performance Shares [Member]	Dec. 13, 2013 Minimum [Member] December 2013 [Member] Absolute TSR [Member] Performance Shares [Member]	Dec. 13, 2013 Maximum [Member] December 2013 [Member] Relative TSR [Member] Performance Shares [Member]	Dec. 13, 2013 Maximum [Member] December 2013 [Member] Absolute TSR [Member] Performance Shares [Member]
Summary of restricted share activity
Unvested shares, Beginning balance	147,881
Unvested weighted average grant date fair value, beginning balance	$ 24.59
Unvested shares, Granted	44,322	72,056							72,118							252,088					66,483
Granted, weighted average grant date fair value	$ 30.11
Vested, shares	(62,047)
Vested, weighted average grant date fair value	$ 23.12
Forfeited, shares	(168)
Forfeited, weighted average grant date fair value	$ 27.57
Unvested shares, Ending balance	129,988
Unvested weighted average grant date fair value, ending balance	$ 27.17
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Percentage of Total Award			30.00%	[1]	30.00%	[1]	40.00%	[2]		30.00%	[1]	30.00%	[1]	40.00%	[2]		50.00%	[1]	50.00%	[1]		30.00%	[1]	30.00%	[1]	40.00%	[2]
Grant Date Fair Value by Component ($ in millions)			$ 0.7	[1]	$ 0.6	[1]	$ 0.7	[2]		$ 0.7	[1]	$ 0.5	[1]	$ 0.7	[2]		$ 4.7	[1]	$ 2.9	[1]		$ 0.7	[1]	$ 0.5	[1]	$ 0.8	[2]
Volatility			33.00%	[1]	33.00%	[1]	33.00%	[2]		31.00%	[1]	31.00%	[1]	31.00%	[2]		29.00%	[1]	29.00%	[1]		29.00%	[1]	29.00%	[1]	29.00%	[2]
Interest Rate			0.34%	[1]	0.34%	[1]	0.34%	[2]		0.41%	[1]	0.41%	[1]	0.41%	[2]							0.62%	[1]	0.62%	[1]	0.62%	[2]	0.34%	0.34%	2.25%	2.25%
Dividend Yield			2.20%	[1]	2.20%	[1]	2.20%	[2]		2.20%	[1]	2.20%	[1]	2.20%	[2]		2.40%	[1]	2.40%	[1]		2.40%	[1]	2.40%	[1]	2.40%	[2]

[1] The Relative Total Shareholder Return and Absolute Total Shareholder Return are market conditions as defined by ASC 718.

[2] The EBITDA Comparison component is a performance condition as defined by ASC 718 and therefore, compensation expense related to this component will be reassessed at each reporting date to determine whether achievement of the target performance condition is probable, and the accrual of compensation expense will be adjusted as appropriate.