SHARE-BASED AWARDS - EXPENSE (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Share-based expense (net of estimated forfeitures)
Total share-based expense	$ 9.8	$ 12.2	$ 8.7
Total recognized tax benefit	(3.8)	(4.8)	(3.4)
Total Share-based expense (net of tax)	6.0	7.4	5.3
Cash received by Matson upon option exercise	1.2	2.2	5.8
Intrinsic value of options exercised	2.0	9.2	3.4
Tax benefit realized upon option exercise	5.9	3.4	1.9
Fair value of stock vested	15.8	8.6	5.0
Non-vested stock and restricted stock units
Share-based expense (net of estimated forfeitures)
Total share-based expense	9.8	12.2	8.4
Non-vested restricted stock units and performance-based equity awards
Share-based expense (net of estimated forfeitures)
Unrecognized compensation cost	$ 11.3
Unrecognized compensation cost, weighted average period for recognition	1 year 9 months 18 days
Stock options
Share-based expense (net of estimated forfeitures)
Total share-based expense			0.3
Total recognized tax benefit	$ (2.2)	$ (2.6)	$ (0.8)
Unrecognized compensation cost	$ 0.0