Equity (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance			$ 93,993
Stock based-awards			15,964
Tax benefit of stock-based awards issued			180
Repurchase of common shares			(144,450)
Dividends paid			(70,933)
Cancellation of common shares			0
Amortization of deferred pension costs, net of tax			317
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax	$ (774)	$ 0	(324)	$ 0
Net income (loss)	33,594	66,650	99,338	191,899
Net income (loss) attributable to non-controlling interest	190	$ 153	(91)	$ 604
Ending balance	(5,915)		(5,915)
Common Shares [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance			1,174
Stock based-awards			0
Tax benefit of stock-based awards issued			0
Repurchase of common shares			0
Dividends paid			0
Cancellation of common shares			(32)
Amortization of deferred pension costs, net of tax			0
Net income (loss)			0
Ending balance	1,142		1,142
Additional Paid-In Capital [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance			0
Stock based-awards			3,181
Tax benefit of stock-based awards issued			180
Repurchase of common shares			0
Dividends paid			0
Cancellation of common shares			(3,092)
Amortization of deferred pension costs, net of tax			0
Net income (loss)			0
Ending balance	269		269
Retained Earnings [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance			415,906
Stock based-awards			(2,094)
Tax benefit of stock-based awards issued			0
Repurchase of common shares			0
Dividends paid			(70,933)
Cancellation of common shares			(206,267)
Amortization of deferred pension costs, net of tax			0
Net income (loss)			99,429
Ending balance	236,041		236,041
Accumulated Other Comprehensive Income (Loss) [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance			(11,894)
Stock based-awards			0
Tax benefit of stock-based awards issued			0
Repurchase of common shares			0
Dividends paid			0
Cancellation of common shares			0
Amortization of deferred pension costs, net of tax			317
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax			(324)
Net income (loss)			0
Ending balance	(11,901)		(11,901)
Treasury Stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance			(317,613)
Stock based-awards			14,877
Tax benefit of stock-based awards issued			0
Repurchase of common shares			(144,450)
Dividends paid			0
Cancellation of common shares			209,391
Amortization of deferred pension costs, net of tax			0
Net income (loss)			0
Ending balance	(237,795)		(237,795)
Non-Controlling Interests [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance			6,420
Stock based-awards			0
Tax benefit of stock-based awards issued			0
Repurchase of common shares			0
Dividends paid			0
Cancellation of common shares			0
Amortization of deferred pension costs, net of tax			0
Ending balance	$ 6,329		$ 6,329