Summary of Significant Accounting Policies - Acquisition (Details) (USD $)	3 Months Ended	12 Months Ended
Dec. 31, 2013	Sep. 27, 2013	Jun. 28, 2013	Mar. 29, 2013	Dec. 31, 2012	Sep. 28, 2012	Jun. 29, 2012	Mar. 30, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2013 Etrinity [Member]	Dec. 31, 2012 Etrinity [Member]	Jan. 31, 2013 Etrinity [Member]
Business Acquisition [Line Items]
Purchase price of acquired entity													$ 2,500,000
Revenues	$ 102,735,000	$ 100,689,000	$ 107,117,000	$ 108,495,000	$ 107,925,000	$ 106,418,000	$ 106,705,000	$ 103,367,000	$ 419,036,000	$ 424,415,000	$ 2,800,000	$ 3,000,000

The total cost of the acquired entity including the cash paid to shareholders of acquired entities, fair value of debt and equity securities issued to shareholders of acquired entities, the fair value of the liabilities assumed, and direct costs of the acquisition.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 141

-Paragraph 51

-Subparagraph d

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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_BusinessAcquisitionCostOfAcquiredEntityPurchasePrice
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant