Condensed Consolidated Statements of Equity (Unaudited) - USD ($) $ in Millions	Total	A&B Share- holders' Equity	Non- controlling interest
Beginning balance at Dec. 31, 2013	$ 1,168.7	$ 1,159.8	$ 8.9
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	56.4	54.4	2.0
Other comprehensive income, net of tax	2.1	2.1
Dividends on common stock	(5.9)	(5.9)
Reclassification of redeemable noncontrolling interest (Note 4)	0.0
Adjustments to redemption value of redeemable noncontrolling interest (Note 4)	0.0
Share-based compensation	3.5	3.5
Shares issued or repurchased, net	(1.1)	(1.1)
Excess tax benefit from share-based awards	1.4	1.4
Ending balance at Sep. 30, 2014	1,225.1	1,214.2	10.9
Beginning balance at Dec. 31, 2014	1,214.8	1,203.9	10.9
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	43.0	41.8	1.2
Other comprehensive income, net of tax	2.2	2.2
Dividends on common stock	(7.4)	(7.4)
Reclassification of redeemable noncontrolling interest (Note 4)	(8.5)		(8.5)
Adjustments to redemption value of redeemable noncontrolling interest (Note 4)	(1.3)	(1.3)
Share-based compensation	3.4	3.4
Shares issued or repurchased, net	(0.9)	(0.9)
Excess tax benefit from share-based awards	0.5	0.5
Ending balance at Sep. 30, 2015	$ 1,245.8	$ 1,242.2	$ 3.6