Goodwill and Other Intangible Assets (Schedule of Goodwill and Other Intangible Assets Included in Equity Method Investments) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Other intangible assets
Gross amount	$ 148,395	$ 148,395
Accumulated impairment losses and amortization	(82,937)	(65,495)
Intangible Assets, Net, Excluding Goodwill [Roll Forward]
Other intangible assets, Net, Beginning of Period	82,900
Other intangible assets, Net, End of Period	65,458	82,900
Intangible Assets, Net, Including Goodwill [Roll Forward]
Goodwill and Other intangible assets, Net, Beginning of Period	265,154
Goodwill and Other intangible assets, Net, End of Period	251,186	265,154
Investments in other ventures, under equity method
Goodwill
Goodwill, Gross amount	12,318	12,318	$ 12,318
Accumulated impairment losses and amortization	(4,500)	(4,500)	0
Goodwill [Roll Forward]
Goodwill, Net, Beginning of Period	7,818	12,318
Acquired during the year		0
Impairment losses		(4,500)
Goodwill, Net, End of Period	7,818	7,818
Other intangible assets
Gross amount	51,796	51,796	45,400
Accumulated impairment losses and amortization	(39,934)	(36,460)	(32,466)
Intangible Assets, Net, Excluding Goodwill [Roll Forward]
Other intangible assets, Net, Beginning of Period	15,336	12,934
Acquired during the year		6,396
Amortization	(3,474)	(2,900)
Impairment losses		(1,094)
Other intangible assets, Net, End of Period	11,862	15,336
Goodwill and Other intangible assets, Total
Gross amount, Beginning of Period	64,114	64,114	57,718
Accumulated impairment losses and amortization, Beginning of Period	(44,434)	(40,960)	$ (32,466)
Intangible Assets, Net, Including Goodwill [Roll Forward]
Goodwill and Other intangible assets, Net, Beginning of Period	23,154	25,252
Acquired during the year		6,396
Amortization	(3,474)	(2,900)
Impairment losses		(5,594)
Goodwill and Other intangible assets, Net, End of Period	$ 19,680	$ 23,154