Consolidated Statements of Shareholders' Equity - USD ($) $ in Thousands	Voting Common Stock [Member] Common Stock [Member]	Nonvoting Common Stock [Member] Common Stock [Member]	Paid-In Capital [Member]	Treasury Stock [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Loss [Member]	Total
Balance at Dec. 31, 2016	$ 216	$ 95	$ 1,019,988	$ (9,592)	$ (826,460)	$ (13,836)	$ 170,411
Balance, shares at Dec. 31, 2016	21,582	9,506		154
Net income (loss)					134,464		134,464
Other comprehensive income (loss)						(18,974)	(18,974)
Comprehensive income (loss)							115,490
Tax Cuts and Jobs Act, reclassification tax effect					4,468	(4,468)
Cumulative effect adjustment attributable to previously unrecognized excess tax benefits on stock-based compensation					4,697		4,697
Balance, shares at Dec. 31, 2017	21,582	9,506		154
Balance at Dec. 31, 2017	$ 216	$ 95	1,019,988	$ (9,592)	(682,831)	(37,278)	290,598
Net income (loss)					9,614		9,614
Other comprehensive income (loss)						23,831	23,831
Comprehensive income (loss)							33,445
Tax Cuts and Jobs Act, reclassification tax effect					4,173	(4,173)
Cumulative effect adjustment attributable to investment in Telesat					(26,477)		(26,477)
Balance, shares at Dec. 31, 2018	21,582	9,506		154
Balance at Dec. 31, 2018	$ 216	$ 95	$ 1,019,988	$ (9,592)	$ (695,521)	$ (17,620)	$ 297,566