Annual report pursuant to Section 13 and 15(d)

Composition of Certain Financial Statement Captions - Summary of available-for-sale securities' fair value and gross unrealized losses (Details)

v3.3.1.900
Composition of Certain Financial Statement Captions - Summary of available-for-sale securities' fair value and gross unrealized losses (Details) - USD ($)
$ in Thousands
Dec. 31, 2015
Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale securities, continuous unrealized loss position, twelve months or less, fair value $ 81,045 $ 197,939
Available-for-sale securities, continuous unrealized loss position, twelve months or less, gross unrealized losses (295) (431)
Available-for-sale securities, continuous unrealized loss position, more than twelve months, fair value 8,531 12,148
Available-for-sale securities, continuous unrealized loss position, more than twelve months, gross unrealized losses (54) (22)
Available-for-sale securities, continuous unrealized loss position, total, fair value 89,576 210,087
Available-for-sale securities, continuous unrealized loss position, total, gross unrealized losses (349) (453)
Corporate debt securities    
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale securities, continuous unrealized loss position, twelve months or less, fair value 64,804 192,699
Available-for-sale securities, continuous unrealized loss position, twelve months or less, gross unrealized losses (293) (422)
Available-for-sale securities, continuous unrealized loss position, more than twelve months, fair value 8,531 12,148
Available-for-sale securities, continuous unrealized loss position, more than twelve months, gross unrealized losses (54) (22)
Available-for-sale securities, continuous unrealized loss position, total, fair value 73,335 204,847
Available-for-sale securities, continuous unrealized loss position, total, gross unrealized losses (347) (444)
U.S. government and government agency debt securities    
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale securities, continuous unrealized loss position, twelve months or less, fair value 16,241 5,240
Available-for-sale securities, continuous unrealized loss position, twelve months or less, gross unrealized losses (2) (9)
Available-for-sale securities, continuous unrealized loss position, more than twelve months, fair value 0 0
Available-for-sale securities, continuous unrealized loss position, more than twelve months, gross unrealized losses 0 0
Available-for-sale securities, continuous unrealized loss position, total, fair value 16,241 5,240
Available-for-sale securities, continuous unrealized loss position, total, gross unrealized losses $ (2) $ (9)