Equity (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification			$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance			155,297
Stock based-awards			17,323
Repurchase of common shares			(8,197)
Dividends paid			(72,861)
Non-controlling interest dividends			(27)
Amortization of deferred pension costs, net of tax			204
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax	$ 42	$ 256	114	$ (1,005)
Net income	21,053	$ 16,838	61,444	$ 48,490
Ending balance	153,297		153,297
Common Shares [Member]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification			0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance			1,148
Stock based-awards			0
Repurchase of common shares			0
Dividends paid			0
Non-controlling interest dividends			0
Amortization of deferred pension costs, net of tax			0
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax			0
Net income			0
Ending balance	1,148		1,148
Additional Paid-In Capital [Member]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification			84
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance			52,850
Stock based-awards			8,834
Repurchase of common shares			0
Dividends paid			0
Non-controlling interest dividends			0
Amortization of deferred pension costs, net of tax			0
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax			0
Net income			0
Ending balance	61,768		61,768
Retained Earnings [Member]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification			(84)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance			187,957
Stock based-awards			0
Repurchase of common shares			0
Dividends paid			(72,861)
Non-controlling interest dividends			0
Amortization of deferred pension costs, net of tax			0
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax			0
Net income			61,434
Ending balance	176,446		176,446
Accumulated Other Comprehensive Income (Loss) [Member]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification			0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance			(9,828)
Stock based-awards			0
Repurchase of common shares			0
Dividends paid			0
Non-controlling interest dividends			0
Amortization of deferred pension costs, net of tax			204
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax			114
Net income			0
Ending balance	(9,510)		(9,510)
Treasury Stock [Member]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification			0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance			(80,773)
Stock based-awards			8,489
Repurchase of common shares			(8,197)
Dividends paid			0
Non-controlling interest dividends			0
Amortization of deferred pension costs, net of tax			0
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax			0
Net income			0
Ending balance	(80,481)		(80,481)
Non-Controlling Interests [Member]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification			0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance			3,943
Stock based-awards			0
Repurchase of common shares			0
Dividends paid			0
Non-controlling interest dividends			(27)
Amortization of deferred pension costs, net of tax			0
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax			0
Net income			10
Ending balance	$ 3,926		$ 3,926