Commitments and Contingencies Obligation Reserves (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Purchased tax credits indemnity reserve
Loss Contingency Accrual [Roll Forward]
Balance at end of period	$ 10.0
Total indemnity reserves
Loss Contingency Accrual [Roll Forward]
Balance at beginning of period	14.7	$ 17.3	$ 17.6
Changes in estimates	0.0	0.0	0.0
Foreign exchange impacts	(0.5)	(2.6)	(0.3)
Balance at end of period	$ 14.2	$ 14.7	$ 17.3