Amount of operating dividend and interest income, including amortization and accretion of premiums and discounts, on available-for-sale securities.

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Available-for-Sale Securities

-URI http://asc.fasb.org/extlink&oid=6505594

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 225

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-04.2)

-URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Paragraph 2

-Article 9

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 35

-Paragraph 4

-URI http://asc.fasb.org/extlink&oid=27723805&loc=d3e24721-111560

Name:	us-gaap_InterestAndDividendIncomeSecuritiesAvailableForSale
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Available-for-Sale Securities - Additional Information (Detail) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jul. 01, 2012	Jun. 30, 2013	Jul. 01, 2012	Dec. 31, 2012
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities	$ 10,467,000		$ 10,467,000		$ 0
Equity securities held in Rabbi Trusts	772,000		772,000
Interest income from available-for-sale securities	100,000	100,000	100,000	100,000
Other Noncurrent Assets [Member]
Schedule of Available-for-sale Securities [Line Items]
Equity securities held in Rabbi Trusts	$ 800,000		$ 800,000