Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 248,904	$ 255,139
Income taxes receivable	10,818	11,105
Other current assets	3,780	3,099
Total current assets	263,502	269,343
Income taxes receivable, non-current	1,550	1,550
Investments in affiliates	84,363	53,430
Deferred tax assets	56,529	50,016
Other assets	52	372
Total assets	405,996	374,711
Current liabilities:
Accrued employment costs	2,166	2,573
Other current liabilities	2,262	1,279
Total current liabilities	4,428	3,852
Pension and other postretirement liabilities	16,390	18,786
Other liabilities	63,390	61,475
Total liabilities	84,208	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	(654,003)	(682,831)
Accumulated other comprehensive loss	(34,916)	(37,278)
Total shareholders' equity	321,788	290,598
Total liabilities and shareholders' equity	405,996	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)
Nonvoting Common Stock [Member]
Common Stock:
Common stock, 0.01 par value	$ 95	$ 95