Capital Transactions - Additional Information (Detail) (USD $) In Millions, except Share data, unless otherwise specified	1 Months Ended	6 Months Ended				3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended
	Apr. 29, 2008	Jun. 30, 2013 Stock	Jul. 01, 2012	Jun. 28, 2013	Jun. 29, 2012	Jun. 30, 2013 Common Stock [Member]	Jul. 01, 2012 Common Stock [Member]	Jun. 30, 2013 Common Stock [Member] Vote	Jul. 01, 2012 Common Stock [Member]	Jun. 30, 2013 Class B Common Stock [Member]	Jul. 01, 2012 Class B Common Stock [Member]	Jun. 30, 2013 Class B Common Stock [Member] Vote	Jul. 01, 2012 Class B Common Stock [Member]	Mar. 05, 2013 Class B Common Stock [Member]	Mar. 06, 2012 Class B Common Stock [Member]	Apr. 29, 2008 Class B Common Stock [Member]	Apr. 29, 2008 Performance Shares [Member]
Schedule of Capitalization, Equity [Line Items]
Number of common class of stock outstanding		2
Dividend is declared and paid on the Common Stock						$ 0.25	$ 0.25	$ 0.50	$ 0.50	$ 0.25	$ 0.25	$ 0.50	$ 0.50
Number of votes per share								1				20
Performance units authorized																	400,000
Common B stock per performance unit																1
Term of performance unit award agreement	10 years
Performance units granted annually																40,000
Maximum goal achievement percentage																100.00%
Performance Unit Award Agreement costs recognized		$ 1.2	$ 1.3
Share price				$ 61.15	$ 64.28
Performance units awarded														40,000	40,000
Performance units awards settled in cash												19,880	17,680
Increase in total number of shares outstanding												20,120	22,320