Debt (Tables)

12 Months Ended

Dec. 31, 2011

Debt Instrument [Line Items]

Short-term borrowings

	December 31,
(in thousands, except percentages)	2011			2010			2009
Maximum amount borrowed	$	601,500		$	305,000		$	92,700
Weighted average interest rate		2.73	%		3.69	%		2.89	%

Recourse [Member]

Debt Instrument [Line Items]

Long-term debt

	December 31,
(in thousands, except percentages)	2011		2010
Note payable, 4.80%, payable at maturity, due 2011	$	—	$	17,000
Note payable, 4.55%, payable at maturity, due 2012		25,000		25,000
Note payable, 5.52 %, payable at maturity, due 2013		25,000		25,000
Note payable, 6.10%, payable at maturity, due 2014		25,000		25,000
Note payable, 6.12%, payable at maturity, due 2015		61,500		61,500
Note payable, 6.78%, payable at maturity due 2018		41,500		41,500
Note payable, variable rate (2.82% at December 31, 2010), payable $110 monthly plus interest, due 2012 (a)		—		10,031
Note payable, variable rate (1.65% at December 31, 2011), payable in increasing amounts ($875 annually at December 31, 2011) plus interest, due 2023 (a)		13,715		14,590
Note payable, variable rate (1.09% at December 31, 2011), payable $58 monthly plus interest, due 2016 (a)		10,150		10,850
Note payable, 8.5%, payable $15 monthly, due 2016		1,160		1,242
Industrial development revenue bonds:
Variable rate (2.76% at December 31, 2011), due 2017 (a)		8,881		9,000
Variable rate (2.19% at December 31, 2011), due 2019 (a)		4,650		4,650
Variable rate (2.25% at December 31, 2011), due 2025 (a)		3,100		3,100
Variable rate (1.87% at December 31, 2011), due 2036 (a)		21,000		—
Debenture bonds, 4.00% to 6.5%, due 2011 through 2021		29,483		36,887
Other notes payable and bonds		—		8
		270,139		285,358
Less: current maturities		32,051		21,683
	$	238,088	$	263,675

(a) Debt is collateralized by first mortgages on certain facilities and related equipment with a book value of $24.5 million

Nonrecourse [Member]

Debt Instrument [Line Items]

Long-term debt

	December 31,
(in thousands, except percentages)	2011		2010
Note payable, 5.96%, payable $218 monthly plus interest, due 2013	$	—	$	14,550
Note payable, 6.37%, payable $24 monthly, due 2014		954		1,405
Note payable, 7.06%, payable $2 monthly, due 2011		—		36
		954		15,991
Less: current maturities		157		2,841
	$	797	$	13,150