Significant Customers and Geographic Information - Revenue by Customer Group (Details) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016 USD ($) customer	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Sep. 30, 2015 USD ($)	Jun. 30, 2015 USD ($)	Mar. 31, 2015 USD ($)	Dec. 31, 2016 USD ($) customer	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Significant Customers and Geographic Information
Revenue, Net	$ 192.7	$ 181.8	$ 175.5	$ 175.4	$ 181.7	$ 173.3	$ 178.0	$ 169.4	$ 725.4	$ 702.4	$ 654.6
U.S. Government
Significant Customers and Geographic Information
Revenue, Net									$ 462.2	$ 447.6	$ 395.3
U.S. Government | Revenue
Significant Customers and Geographic Information
Concentration risk percentage									63.70%	63.70%	60.40%
U.S. Government | Net accounts receivable
Significant Customers and Geographic Information
Concentration risk percentage									30.60%	36.60%
Diversified commercial
Significant Customers and Geographic Information
Revenue, Net									$ 263.2	$ 254.8	$ 259.3
DAP Customer | Net accounts receivable
Significant Customers and Geographic Information
Concentration risk percentage									16.50%
Number of customers | customer	1								1
DAP Customer | Net accounts receivable | Maximum
Significant Customers and Geographic Information
Concentration risk percentage										10.00%