Components of Other Intangible Assets (Detail) (USD $) In Thousands, unless otherwise specified	6 Months Ended
Jun. 30, 2012	Dec. 31, 2011
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 44,856	$ 32,869
Accumulated Amortization	9,262	7,827
Customer Relationships
Finite-Lived Intangible Assets [Line Items]
Weighted Average Life	18 years 2 months 12 days
Gross Carrying Amount	44,161	32,520
Accumulated Amortization	9,108	7,771
Other Intangible Assets
Finite-Lived Intangible Assets [Line Items]
Weighted Average Life	3 years
Gross Carrying Amount	695	349
Accumulated Amortization	$ 154	$ 56

Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 30

-Section 50

-Paragraph 2

-Subparagraph (a)(1)

-URI http://asc.fasb.org/extlink&oid=7658586&loc=d3e16323-109275

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 142

-Paragraph 45

-Subparagraph a(1)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Name:	us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant