Share-Based Compensation - Narrative (Details) - USD ($)	1 Months Ended						12 Months Ended
	Mar. 31, 2017	Feb. 28, 2017	Mar. 31, 2016	Feb. 29, 2016	Mar. 31, 2015	Feb. 28, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Jun. 30, 2017
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Capitalized share-based compensation costs							$ 0	$ 0	$ 0
Repurchase of common stock for employee tax withholding obligations amount, shares							41,532	25,432	35,649
Repurchased shares							0	0	141,462
Common stock purchased for treasury									$ 3,800,000
2017 Plan
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Useful Life of the plan							10 years
Common stock shares issuable										1,750,000
Shares available for grant							1,744,546
2007 Plan
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Award vesting period							3 years
Performance Unit Incentive Plan (“PUP”) | 2007 Plan
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Awards granted during the period							$ 3,500,000
Stock value payable							1,400,000
Liability awards recorded							11,000,000	$ 7,600,000
Payments to employees	$ 3,700,000		$ 200,000		$ 2,400,000
Restricted Stock | 2007 Plan
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Grant date fair value of restricted stock vested							2,700,000	$ 2,000,000	$ 2,200,000
Unamortized cost							$ 2,500,000
Recognition period of unrecognized cost							1 year 2 months 12 days
Repurchase of common stock for employee tax withholding obligations amount, shares							41,532	25,432	35,649
Repurchase of common stock for employee tax withholding obligations amount							$ 2,100,000	$ 700,000	$ 1,000,000
Repurchased shares									141,462
Common stock purchased for treasury									$ 3,800,000
Restricted Stock Units | 2007 Plan
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Payments to employees		$ 300,000		$ 200,000		$ 300,000
Liabilities related to restricted stock							500,000	$ 400,000
Stock Options | 2007 Plan
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Unamortized cost							$ 0
Exercised							0
Forfeited or expired							0
Exercisable							63,773	63,773
Outstanding							63,773	63,773
Weighted-average exercise price							$ 16.62	$ 16.62
Weighted average remaining contractual life							2 years	2 years
Restructuring Charges | Performance Unit Incentive Plan (“PUP”)
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based compensation before income tax benefit							$ 100,000	$ 200,000	$ 45,000