Investments - Equity Method Investments (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Jan. 31, 2015	Dec. 31, 2014	May. 31, 2014
Schedule of Equity Method Investments [Line Items]
Carrying Value	$ 44,253		$ 44,253			$ 30,060
Income (Loss) Recognized	$ 5,445	$ 2,874	$ 3,335	$ 1,441
Again Faster
Schedule of Equity Method Investments [Line Items]
Ownership (as a percent)	40.00%		40.00%			40.00%
Carrying Value	$ 2,549		$ 2,549			$ 3,105
Income (Loss) Recognized	$ (135)	(164)	$ (557)	(293)
iGo
Schedule of Equity Method Investments [Line Items]
Ownership (as a percent)	46.90%		46.90%			46.90%
Carrying Value	$ 2,870		$ 2,870			$ 2,600
Income (Loss) Recognized	$ (14)	(501)	$ 271	(1,805)
API
Schedule of Equity Method Investments [Line Items]
Ownership (as a percent)	20.60%		20.60%			20.60%	20.60%
Carrying Value	$ 28,700		$ 28,700			$ 24,355
Income (Loss) Recognized	$ 5,031	3,539	$ 4,345	3,539
Aviat
Schedule of Equity Method Investments [Line Items]
Ownership (as a percent)	12.90%		12.90%		12.90%
Carrying Value	$ 10,134		$ 10,134
Income (Loss) Recognized	$ 563	$ 0	$ (724)	$ 0