Segment Results (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015		Mar. 31, 2014
Segment Reporting Information [Line Items]
Revenue	$ 150.7		$ 94.8
Operating profit	54.3		14.3
Interest expense	(7.1)		(7.2)
General corporate expenses	5.6		5.2
Reduction in KRS II carrying value	(0.1)		0
Income From Continuing Operations Before Income Taxes	41.5		1.9
Income tax expense	15.6		0.8
Income From Continuing Operations	25.9		1.1
Income From Discontinued Operations (net of income taxes)	0		34.3
Net Income	25.9		35.4
Income attributable to noncontrolling interest	(0.6)		(0.4)
Net Income Attributable to A&B Shareholders	25.3		35.0
Leasing
Segment Reporting Information [Line Items]
Revenue	32.7	[1]	31.2	[1]
Operating profit	13.2	[1]	11.8	[1]
Development and sales
Segment Reporting Information [Line Items]
Revenue	36.5	[1]	71.0	[1]
Operating profit	32.0	[1]	52.3	[1]
Less amounts reported in discontinued operations
Segment Reporting Information [Line Items]
Revenue	0	[1]	70.4	[1]
Operating profit	0	[1]	56.2	[1]
Materials and construction
Segment Reporting Information [Line Items]
Revenue	56.9		50.1
Operating profit	7.2		3.4
Agribusiness
Segment Reporting Information [Line Items]
Revenue	28.9		12.9
Operating profit	1.9		3.0
Reconciling item
Segment Reporting Information [Line Items]
Revenue	$ (4.3)	[2]	$ 0	[2]
COLORADO | Retail Site
Segment Reporting Information [Line Items]
Area of real estate property sold	46,500

[1] Prior year amounts recast for amounts treated as discontinued operations.

[2] Represents the deduction of revenue from the sale of a 46,500 square foot retail property in Colorado that is classified as "Gain on sale of improved property" in the Condensed Consolidated Statements of Income, but reflected as revenue for segment reporting purposes.