Pending Merger with Nielsen - Additional Information (Detail) (Nielsen Holdings, USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2012
Nielsen Holdings
Business Acquisition [Line Items]
Merger costs	$ 5.2
Net of tax impact to net income	$ 4.9

The net of tax impact to net income of consulting and legal service expenses incurred during the period in association with pursuing the pending merger with Nielsen Holdings.

No definition available.

Name:	arb_NetOfTaxImpactOnNetIncomeOfMergerCosts
Namespace Prefix:	arb_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration