Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 250,137	$ 255,139
Income taxes receivable	10,827	11,105
Other current assets	3,552	3,099
Total current assets	264,516	269,343
Income taxes receivable, non-current	1,550	1,550
Investments in affiliates	36,383	53,430
Deferred tax assets	60,888	50,016
Other assets	361	372
Total assets	363,698	374,711
Current liabilities:
Accrued employment costs	1,685	2,573
Other current liabilities	1,997	1,279
Total current liabilities	3,682	3,852
Pension and other postretirement liabilities	16,405	18,786
Other liabilities	62,607	61,475
Total liabilities	82,694	84,113
Commitments and contingencies
Shareholders' Equity:
Preferred stock, 0.01 par value; 10,000,000 shares authorized, no shares issued and outstanding
Common Stock:
Paid-in capital	1,019,988	1,019,988
Accumulated deficit	(700,197)	(682,831)
Accumulated other comprehensive loss	(29,506)	(37,278)
Total shareholders' equity	281,004	290,598
Total liabilities and shareholders' equity	363,698	374,711
Voting Common Stock [Member]
Common Stock:
Common stock, 0.01 par value	216	216
Treasury stock (at cost), 154,494 shares of voting common stock	(9,592)	(9,592)
Non-Voting Common Stock [Member]
Common Stock:
Common stock, 0.01 par value	$ 95	$ 95