Consolidated Statements of Comprehensive Income (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Statement of Comprehensive Income [Abstract]
Net income	$ 64.5		$ 34.8		$ 18.8
Defined benefit pension plans:
Net gain (loss) / prior service credit (cost)	(26.7)		22.4		(6.0)
Amortization of net loss included in net periodic pension cost	4.5	[1]	7.7	[1]	8.0	[1]
Amortization of prior service credit included in net periodic pension cost	(1.3)	[1]	(1.3)	[1]	(1.3)	[1]
Income taxes related to other comprehensive income	9.2		(11.7)		(0.3)
Other Comprehensive Income (Loss)	(14.3)		17.1		0.4
Comprehensive Income	50.2		51.9		19.2
Comprehensive income attributable to non-controlling interest	(3.1)		(0.5)		0
Comprehensive income attributable to A&B	$ 47.1		$ 51.4		$ 19.2

[1] These accumulated other comprehensive income components are included in the computation of net periodic pension cost (see Note 12 for additional details).