Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 255,198	$ 259,067
Income tax refund receivable	1,193	576
Other current assets	1,600	1,322
Total current assets	257,991	260,965
Right-of-use asset	831	988
Income tax refund receivable, non-current		387
Investments in affiliates	4,173	90,184
Deferred tax assets	36,301	37,945
Other assets	340	341
Total assets	299,636	390,810
Current liabilities:
Accrued employment costs	1,132	2,611
Other current liabilities	2,204	2,883
Total current liabilities	3,336	5,494
Pension and other postretirement liabilities	17,061	17,447
Other liabilities	19,265	17,842
Total liabilities	39,662	40,783
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	(727,109)	(605,766)
Accumulated other comprehensive loss	(23,624)	(54,914)
Total shareholders' equity	259,974	350,027
Total liabilities and shareholders' equity	299,636	390,810
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