Balance Sheet Components - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Property Plant And Equipment [Abstract]
Depreciation	$ 3.3	$ 3.4	$ 9.6	$ 9.6
Capitalized costs	0.3	0.3	1.1	2.5
Amortization expense recognized	2.4	$ 2.1	7.0	$ 5.5
Unamortized costs	$ 13.1		$ 13.1		$ 19.0