Borrowings - 2006 Credit Agreement (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Borrowings
Interest expense including amortization of debt issuance costs and net settlement payments on interest rate swaps	$ 1.8	$ 2.3	$ 2.7