Fair Value Measurements (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Trading equity securities [Abstract]
SERP money market fund	$ 989	$ 1,516
SERP mutual funds	1,732	1,158
Preferred stocks	441	562
Trading debt securities [Abstract]
Corporate bonds	3,887	5,446
Municipal bonds	3,091	3,837
Floating rate notes	330	225
U.S. Treasury bill	250
Other government bonds	343	84
Derivative financial instruments	307
Pension assets	9,378	9,376
Total financial assets	20,748	22,204
Financial Liabilities [Abstract]
SERP liabilities	6,076	5,807
Derivative financial instruments	50	1,251
Total financial liabilities	6,126	7,058
Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Trading equity securities [Abstract]
SERP money market fund	989	1,516
SERP mutual funds	1,732	1,158
Preferred stocks	441	562
Trading debt securities [Abstract]
Corporate bonds	1,649	0
Municipal bonds	211	0
Floating rate notes	97	0
U.S. Treasury bill	250
Other government bonds	0	0
Derivative financial instruments	0
Pension assets	9,378	9,376
Total financial assets	14,747	12,612
Financial Liabilities [Abstract]
SERP liabilities	6,076	5,807
Derivative financial instruments	0	0
Total financial liabilities	6,076	5,807
Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Trading equity securities [Abstract]
SERP money market fund	0	0
SERP mutual funds	0	0
Preferred stocks	0	0
Trading debt securities [Abstract]
Corporate bonds	2,238	5,446
Municipal bonds	2,880	3,837
Floating rate notes	233	225
U.S. Treasury bill	0
Other government bonds	343	84
Derivative financial instruments	307
Pension assets	0	0
Total financial assets	6,001	9,592
Financial Liabilities [Abstract]
SERP liabilities	0	1,251
Derivative financial instruments	50	0
Total financial liabilities	50	1,251
Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Trading equity securities [Abstract]
SERP money market fund	0	0
SERP mutual funds	0	0
Preferred stocks	0	0
Trading debt securities [Abstract]
Corporate bonds	0	0
Municipal bonds	0	0
Floating rate notes	0	0
U.S. Treasury bill	0
Other government bonds	0	0
Derivative financial instruments	0
Pension assets		0
Total financial assets	0	0
Financial Liabilities [Abstract]
SERP liabilities	0	0
Derivative financial instruments	0	0
Total financial liabilities	$ 0	$ 0