Supplementary Balance Sheet Information - Additional Information (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Asset capitalized under capital lease	$ 10.4us-gaap_CapitalLeasedAssetsGross
Capitalized software development costs	$ 0.2	$ 0.2	$ 0.6

Amount before accumulated amortization of capitalized costs for computer software, including but not limited to, acquired and internally developed computer software.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 985

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=6501960&loc=d3e128462-111756

Name:	us-gaap_CapitalizedComputerSoftwareGross
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant