v3.19.3.a.u2
Other long-term liabilities (Details) - USD ($)
$ in Millions
3 Months Ended 12 Months Ended
Dec. 31, 2017
Dec. 31, 2019
Dec. 31, 2018
Long-term contract liability   $ 0.2  
Net pension liability   1.2 $ 1.2
Accrued LTIP and director share units   1.6 1.4
Other   1.7 2.4
Other long-term liabilities   4.7 5.0
Asset retirement obligations rollforward      
Asset retirement obligations beginning of year   49.2 45.3
Accretion and change in estimate of asset retirement obligation   2.3 4.3
Acquisition     1.8
Costs incurred   (1.0) (0.5)
Translation adjustments   1.0 (1.7)
Asset retirement obligations, end of year $ 45.3 51.5 49.2
San Diego Projects      
Asset retirement obligations rollforward      
Acquisition 6.7    
Amortization expense of intangible assets 5.0    
Amount of increase in asset retirement obligations   $ 1.4 $ 3.5
Asset Impairment Charges      
Project removal obligation $ 1.7