Stock-Based Compensation Restricted Stock Units (Details) $ / shares in Units, $ in Millions		12 Months Ended
		Dec. 31, 2015 USD ($) years $ / shares shares	Dec. 31, 2014 USD ($) $ / shares shares	Dec. 31, 2013 USD ($) $ / shares shares	Dec. 31, 2011 $ / shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense | $		$ 0.5
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested [Roll Forward]
Incentive share awards exercisable Aggregate Intrinsic Value (in millions) | $		$ 1.7
Restricted Stock, Shares Issued Net of Shares for Tax Withholdings		78,182
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value | $ / shares		$ 18.59	$ 13.93	$ 11.48	$ 8.46
Allocated Share-based Compensation Expense | $		$ 1.7	$ 2.1	$ 2.1
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested [Roll Forward]
Beginning balance		453,146	512,085
Incentive shares granted		69,744	122,649	108,174
Incentive share awards cancelled		(14,544)	(11,021)	0
Ending balance		282,701	453,146	512,085
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value | $ / shares		$ 17.04	$ 17.93	$ 20.49
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Period Increase (Decrease)		(225,645)	(170,567)	(221,138)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value | $ / shares		$ 8.71	$ 9.54	$ 7.37
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition		1 year 2 months 19 days
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Intrinsic Value, Amount Per Share | $ / shares		$ 19.29	$ 12.35
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense | $		$ 3.5	$ 3.0	$ 2.7
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized | $		$ 4.2
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested [Roll Forward]
Beginning balance		593,613	752,595	960,388
Incentive shares granted		252,629	123,982	166,474
Incentive share awards vested		(285,495)	(253,834)	(350,107)
Incentive share awards cancelled		(24,765)	(29,130)	(24,160)
Ending balance		535,982	593,613	752,595
Incentive share awards outstanding Weighted Average Contractual Term (in years)		1 year 3 months 18 days
Incentive share awards outstanding Aggregate Intrinsic Value (in millions) | $ / shares		$ 9,700,000
Vested and expected to vest	[1]	503,552
Vested and expected to vest Weighted Average Contractual Term (in years) | $	[1]	$ 9.1
Incentive share awards exercisable		0
Incentive share awards exercisable Weighted Average Contractual Term (in years) | years		0
Incentive share awards exercisable Aggregate Intrinsic Value (in millions) | $		$ 0.0
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition		1 year 2 months 12 days

[1] Incentive shares expected to vest based upon historical forfeitures rate