Associate (Employee) Benefit Plans (Net Periodic Benefit Cost Components of Post Retirement Benefits) (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost	$ 148	$ 116	$ 443	$ 350
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	72	52	216	156
Interest cost	44	41	131	125
Amortization of transition obligation	15	15	45	45
Net loss recognition	$ 17	$ 8	$ 51	$ 24