Investments (Details) Tables - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Debt securities: corporate bonds, Cost	$ 4,458	$ 8,909
Cost	14,797	23,689
Gross Unrealized Gains	7,925	7,533
Gross Unrealized Losses	(132)	(190)
Debt securities: corporate bonds, Carrying Value	4,453	9,042
Carrying Value	22,590	31,032
Available-for-sale Securities, Debt Maturities [Abstract]
Amortized Cost, Due in one year or less	38	3,786
Amortized Cost, Due after one year through five years	2,603	3,310
Amortized Cost, Due after five years	1,817	1,813
Amortized Cost	4,458	8,909
Carrying Value, Due in one year or less	37	3,958
Carrying Value, Due after one year through five years	2,566	3,255
Carrying Value, Due after five years	1,850	1,829
Carrying Value	4,453	9,042
Gross realized gains:	1,429	5,552	$ 24,113
Gross realized losses:	(21,024)	(1,897)	(471)
Net realized gain (loss)	(19,595)	3,655	$ 23,642
Impairment loss on investment in unconsolidated affiliate	20,696	1,078
Other Investments	$ 3,482	$ 24,639
Synthonics
Available-for-sale Securities, Debt Maturities [Abstract]
Cost Method, Ownership Percentage	18.30%	19.60%
Cost method investments	$ 2,170	$ 2,170
Mindjet
Available-for-sale Securities, Debt Maturities [Abstract]
Impairment loss on investment in unconsolidated affiliate	$ 20,700	1,100
Voting Interest Percentage	19.30%
Other Investments	$ 2,200
Corporate Bond Securities
Schedule of Available-for-sale Securities [Line Items]
Debt securities: corporate bonds, Cost	4,458	8,909
Gross Unrealized Gains	46	198
Gross Unrealized Losses	(51)	(65)
Debt securities: corporate bonds, Carrying Value	4,453	9,042
Available-for-sale Securities, Debt Maturities [Abstract]
Amortized Cost	4,458	8,909
Carrying Value	4,453	9,042
Equity Securities
Schedule of Available-for-sale Securities [Line Items]
Marketable equity securities, Cost	10,339	14,780
Gross Unrealized Gains	7,879	7,335
Gross Unrealized Losses	(81)	(125)
Marketable equity securities, Carrying Value	$ 18,137	$ 21,990
Equity Securities | Mindjet
Available-for-sale Securities, Debt Maturities [Abstract]
Cost Method, Ownership Percentage		13.40%
Cost method investments	$ 1,312	$ 15,858
Equity Method Investment, Ownership Percentage	19.30%	15.00%
Equity Method Investments	$ 0	$ 6,611
Voting Interest Percentage	19.30%	28.40%
Other Investments	$ 1,312	$ 22,469
Debt Securities
Available-for-sale Securities, Debt Maturities [Abstract]
Gross realized gains:	419	7	$ 3
Gross realized losses:	(4)	(116)	(152)
Equity Securities and Other Investments
Available-for-sale Securities, Debt Maturities [Abstract]
Gross realized gains:	1,010	5,545	24,110
Gross realized losses:	$ (21,020)	$ (1,781)	$ (319)