Condensed Consolidated Statements of Equity (Unaudited) - USD ($)		Total	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Accumulated Other Comprehensive Loss	Noncontrolling Interest [Member]
Equity, beginning balance (Beginning balance previously reported) at Dec. 31, 2015			$ 838,000	$ 1,163,985,000	$ (174,038,000)	$ (89,802,000)
Equity, beginning balance (Adjustment for adoption of new accounting guidance) at Dec. 31, 2015			0	(58,000)	14,808,000	0
Equity, beginning balance at Dec. 31, 2015			838,000	1,163,927,000	(159,230,000)	(89,802,000)
Equity, Noncontrolling Interest, beginning balance (Beginning balance previously reported) at Dec. 31, 2015							$ 0
Equity, Noncontrolling Interest, beginning balance (Adjustment for adoption of new accounting guidance) at Dec. 31, 2015							0
Equity, Noncontrolling Interest, beginning balance at Dec. 31, 2015							0
Total Equity, beginning balance (Beginning balance previously reported) at Dec. 31, 2015		$ 900,983,000
Total Equity, beginning balance (Adjustment for adoption of new accounting guidance) at Dec. 31, 2015		14,750,000
Total Equity, beginning balance at Dec. 31, 2015		915,733,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)		16,376,000			16,376,000
Changes in defined benefit pension plans		1,282,000				1,282,000
Changes in fair value of derivative		118,000				118,000
Repurchase Class A Common shares: 321,891 in 2017 and 1,108,000 in 2016		(18,686,000)	(11,000)	(17,280,000)	(1,395,000)
Compensation plans: 525,392 net shares issued in 2017 and 824,900 in 2016	[1]	9,592,000	8,000	9,584,000
Other		(14,000)				(14,000)
Equity, ending balance at Jun. 30, 2016			835,000	1,156,231,000	(144,249,000)	(88,416,000)
Equity, Noncontrolling Interest, beginning balance at Jun. 30, 2016							0
Total Equity, ending balance at Jun. 30, 2016		924,401,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Tax payments related to shares withheld for vested stock and RSUs		2,603
Equity, beginning balance at Dec. 31, 2016		945,935,000	819,000	1,132,540,000	(94,077,000)	(93,347,000)
Equity, Noncontrolling Interest, beginning balance at Dec. 31, 2016		0					0
Total Equity, beginning balance at Dec. 31, 2016		945,935,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)		6,606,000			6,606,000
Changes in defined benefit pension plans		1,390,000				1,390,000
Changes in fair value of derivative		0
Repurchase Class A Common shares: 321,891 in 2017 and 1,108,000 in 2016		(6,257,000)	(3,000)	(5,008,000)	(1,246,000)
Compensation plans: 525,392 net shares issued in 2017 and 824,900 in 2016	[1]	7,764,000	5,000	7,759,000
Formation of venture		2,143,000					2,143,000
Other		(32,000)				(32,000)
Equity, ending balance at Jun. 30, 2017		955,406,000	$ 821,000	$ 1,135,291,000	$ (88,717,000)	$ (91,989,000)
Equity, Noncontrolling Interest, beginning balance at Jun. 30, 2017		2,143,000					$ 2,143,000
Total Equity, ending balance at Jun. 30, 2017		957,549,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Tax payments related to shares withheld for vested stock and RSUs		$ 3,340

[1] * Net of tax payments related to shares withheld for vested stock and RSUs of $3,340 in 2017 and $2,603 in 2016.