The proposed termination fee that would be received by the entity in the event that the acquiring entity cancels the agreement.

No definition available.

Name:	aco_SubsequentEventBusinessCombinationTerminationFee
Namespace Prefix:	aco_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Subsequent Event (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	Feb. 26, 2014 Imerys SA [Member]	Feb. 24, 2014 Subsequent Event [Member]	Feb. 11, 2014 Subsequent Event [Member] Imerys SA [Member]	Feb. 24, 2014 Subsequent Event [Member] Mineral Technologies, Inc "MTI" [Member]
Subsequent Event [Line Items]
Purchase price of acquisition (in dollars per share)	$ 42.75	$ 42.5	$ 41.00
Reverse termination fee, in event of termination				$ 70