Condensed Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ (4.7)	$ (1.2)	$ 0.9	$ 7.5
Other Comprehensive Income (Loss), net of tax:
Unrealized interest rate hedging gain (loss)	(0.7)	(2.0)	(7.6)	(3.5)
Impact of reclassification adjustment to interest expense included in Net Income (Loss)	0.1	(0.2)	0.1	(0.3)
Defined benefit plans:
Amortization of net loss included in net periodic benefit cost	0.6	1.0	1.2	2.0
Amortization of prior service credit included in net periodic benefit cost	0.0	(0.2)	0.0	(0.3)
Income taxes related to other comprehensive income (loss)	0.0	0.0	0.0	0.0
Other comprehensive income (loss), net of tax	0.0	(1.4)	(6.3)	(2.1)
Comprehensive Income (Loss)	(4.7)	(2.6)	(5.4)	5.4
Comprehensive income (loss) attributable to noncontrolling interest	0.0	0.4	0.6	0.7
Comprehensive Income (Loss) Attributable to A&B Shareholders	$ (4.7)	$ (2.2)	$ (4.8)	$ 6.1