v3.3.1.900
Fair Value of Financial Instruments (Contractual Maturity) (Details) - USD ($)
$ in Thousands
Dec. 31, 2015
Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]    
Mature within One Year $ 113,614 $ 52,014
After One Year through Two Years 39,699 30,681
Over Two Years 3,578 8,767
Fair Value 156,891 91,462
Commercial paper    
Schedule of Available-for-sale Securities [Line Items]    
Mature within One Year 27,794 5,999
After One Year through Two Years 0 0
Over Two Years 0 0
Fair Value 27,794 5,999
U.S. government agencies    
Schedule of Available-for-sale Securities [Line Items]    
Mature within One Year 73,385 33,577
After One Year through Two Years 32,541 20,255
Over Two Years 0 0
Fair Value 105,926 53,832
Corporate bonds    
Schedule of Available-for-sale Securities [Line Items]    
Mature within One Year 12,435 12,438
After One Year through Two Years 3,747 3,099
Over Two Years 0 0
Fair Value 16,182 15,537
Asset-backed securities    
Schedule of Available-for-sale Securities [Line Items]    
Mature within One Year 0 0
After One Year through Two Years 3,411 7,327
Over Two Years 3,578 8,767
Fair Value $ 6,989 $ 16,094