Accelerated tax depreciation | Other temporary differences | Tax losses | Retirement benefit obligations | Total | ||||||||||||
$M | $M | $M | $M | $M | ||||||||||||
At January 1, 2016 | (11.0 | ) | 5.1 | 4.7 | 13.3 | 12.1 | ||||||||||
Credited/(charged) to consolidated income statement | 0.1 | (2.1 | ) | 0.9 | (1.2 | ) | (2.3 | ) | ||||||||
Credited to other comprehensive income | — | — | — | 4.3 | 4.3 | |||||||||||
Exchange difference | — | (0.2 | ) | (0.5 | ) | (1.7 | ) | (2.4 | ) | |||||||
At December 31, 2016 | (10.9 | ) | 2.8 | 5.1 | 14.7 | 11.7 | ||||||||||
Credited/(charged) to consolidated income statement | 5.2 | (1.0 | ) | — | 0.6 | 4.8 | ||||||||||
Charged to other comprehensive income | — | (0.6 | ) | — | (5.2 | ) | (5.8 | ) | ||||||||
Credited to equity | — | 0.6 | — | — | 0.6 | |||||||||||
Exchange difference | — | 0.2 | 0.3 | 0.8 | 1.3 | |||||||||||
At December 31, 2017 | (5.7 | ) | 2.0 | 5.4 | 10.9 | 12.6 |