Employee Benefit Plans Narrative (Detail) (USD $) In Millions, unless otherwise specified	9 Months Ended	3 Months Ended
Jun. 30, 2013	Dec. 31, 2012 Nexus Plan
Defined Benefit Plan Disclosure [Line Items]
Accelerated amortization of prior pension losses	$ 0.1	$ 0.1

The amount of the prior service cost or credit recognized in net periodic benefit cost relating to benefit changes attributable to plan participants' prior service pursuant to a plan amendment or a plan initiation.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (h)(1)

-URI http://asc.fasb.org/extlink&oid=28361610&loc=d3e1928-114920

Name:	us-gaap_DefinedBenefitPlanAmortizationOfPriorServiceCostCredit
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration