Investments and Fair Value Measurements - Investment Category and Length (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2016	Dec. 31, 2015
Summary of fair value and gross unrealized losses related to available-for-sale securities [Abstract]
Fair value, in loss position less than twelve months	$ 8,601	$ 11,375
Gross unrealized loss, in loss position less than twelve months	(26)	(67)
Fair value, in loss position greater than twelve months	4,844	5,390
Gross unrealized loss, in loss position greater than twelve months	(7)	(9)
Fair value, total in loss position	13,445	16,765
Gross unrealized loss, total in loss position	(33)	(76)
Minority Investments
Investments in privately-held companies	7,025	7,948
Certificates of Deposit [Member]
Summary of fair value and gross unrealized losses related to available-for-sale securities [Abstract]
Fair value, in loss position less than twelve months	3,541	4,509
Gross unrealized loss, in loss position less than twelve months	(9)	(11)
Fair value, in loss position greater than twelve months	1,440	3,543
Gross unrealized loss, in loss position greater than twelve months		(2)
Fair value, total in loss position	4,981	8,052
Gross unrealized loss, total in loss position	(9)	(13)
Corporate Bonds [Member]
Summary of fair value and gross unrealized losses related to available-for-sale securities [Abstract]
Fair value, in loss position less than twelve months	5,060	6,866
Gross unrealized loss, in loss position less than twelve months	(17)	(56)
Fair value, in loss position greater than twelve months	3,404	1,847
Gross unrealized loss, in loss position greater than twelve months	(7)	(7)
Fair value, total in loss position	8,464	8,713
Gross unrealized loss, total in loss position	(24)	(63)
Other Assets [Member]
Minority Investments
Investments in privately-held companies	$ 10,500	$ 12,100