Stockholders' Equity, Preferred and Common Stock (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Common Stock [Abstract]
Common stock, shares authorized to issue (in shares)	300,000,000	300,000,000
Common stock, shares issued (in shares)	120,351,480	118,442,726
Common stock, shares outstanding (in shares)	120,351,480	118,442,726
Net proceeds from stock option exercises, vesting of restricted stock units, and ESPP purchases	$ 24,888	$ 23,071	$ 62,958
Preferred Stock [Member]
Preferred Stock [Abstract]
Preferred stock, shares authorized to issue (in shares)	15,000,000
Preferred stock, shares issued (in shares)		0
Preferred stock, shares outstanding (in shares)	0
Series C Junior Participating Preferred Stock [Member]
Preferred Stock [Abstract]
Preferred stock, shares issued (in shares)		0
Preferred stock, shares outstanding (in shares)		0
Common Stock [Member]
Common Stock [Abstract]
Common stock, shares authorized to issue (in shares)	300,000,000	300,000,000
Common stock, shares issued (in shares)	120,351,480	118,442,726
Common stock, shares outstanding (in shares)	120,351,480	118,442,726
Common shares reserved for future issuance (in shares)	18,512,177
Number of shares issued for stock option exercises, vesting of restricted stock units, and ESPP purchases (in shares)	1,908,000	1,972,000	5,372,000
Net proceeds from stock option exercises, vesting of restricted stock units, and ESPP purchases	$ 24,900	$ 23,100	$ 63,000