Contingently Issuable Common Stock (Details) (USD $) Share data in Millions, except Per Share data, unless otherwise specified	12 Months Ended			0 Months Ended	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 10, 2010 Nellix	Dec. 31, 2013 Nellix
Business Acquisition [Line Items]
Purchase price of common shares				3.2
Value of common shares				$ 19,400,000
Maximum shares issuable				10.2	3.5
Fair value of contingent payment	60,900,000	52,400,000		28,200,000
Closing stock price					$ 17.44
Contingent consideration, at fair value hypothetical value					61,000,000
Increase (decrease) common stock					$ 3.20
Percentage increase (decrease)					22.00%
Fair Value of Contingently Issuable Common Stock [Roll Forward]
December 31, 2011	52,400,000
Change in fair value of contingent consideration related to acquisition	8,500,000	13,700,000	10,500,000
December 31, 2012	60,900,000	52,400,000		28,200,000
Current liabilities, contingently issuable common stock					$ 46,500,000