Quarterly report pursuant to Section 13 or 15(d)

Cash, Cash Equivalents and Investments - Summary of available-for-sale securities' fair value and gross unrealized losses (Details)

v3.2.0.727
Cash, Cash Equivalents and Investments - Summary of available-for-sale securities' fair value and gross unrealized losses (Details) - USD ($)
$ in Thousands
Jun. 30, 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 $ 135,552 $ 197,939
Available-for-sale securities, continuous unrealized loss position, twelve months or less, gross unrealized loss (188) (431)
Available-for-sale securities, continuous unrealized loss position, twelve months or longer, fair value 19,738 12,148
Available-for-sale securities, continuous unrealized loss position, twelve months or longer, gross unrealized loss (21) (22)
Available-for-sale securities, continuous unrealized loss position, fair value 155,290 210,087
Available-for-sale securities, continuous unrealized loss position, gross unrealized loss (209) (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 135,552 192,699
Available-for-sale securities, continuous unrealized loss position, twelve months or less, gross unrealized loss (188) (422)
Available-for-sale securities, continuous unrealized loss position, twelve months or longer, fair value 19,738 12,148
Available-for-sale securities, continuous unrealized loss position, twelve months or longer, gross unrealized loss (21) (22)
Available-for-sale securities, continuous unrealized loss position, fair value 155,290 204,847
Available-for-sale securities, continuous unrealized loss position, gross unrealized loss (209) (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 0 5,240
Available-for-sale securities, continuous unrealized loss position, twelve months or less, gross unrealized loss 0 (9)
Available-for-sale securities, continuous unrealized loss position, twelve months or longer, fair value 0 0
Available-for-sale securities, continuous unrealized loss position, twelve months or longer, gross unrealized loss 0 0
Available-for-sale securities, continuous unrealized loss position, fair value 0 5,240
Available-for-sale securities, continuous unrealized loss position, gross unrealized loss $ 0 $ (9)