Statement of Accounting Policy (Details) (USD $)	3 Months Ended		6 Months Ended		3 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013 Foreign currency	Mar. 31, 2013 Foreign currency	Jun. 30, 2012 Foreign currency	Mar. 31, 2012 Foreign currency	Jun. 30, 2013 Defined benefit pension plans	Mar. 31, 2013 Defined benefit pension plans	Jun. 30, 2012 Defined benefit pension plans	Mar. 31, 2012 Defined benefit pension plans	Jun. 30, 2013 Accumulative Other Comprehensive Income	Mar. 31, 2013 Accumulative Other Comprehensive Income	Jun. 30, 2012 Accumulative Other Comprehensive Income	Mar. 31, 2012 Accumulative Other Comprehensive Income	Jun. 30, 2013 Carrying (Reported) Amount, Fair Value Disclosure [Member] Senior notes	Jun. 30, 2013 Estimate of Fair Value, Fair Value Disclosure [Member] Senior notes	Dec. 31, 2012 Estimate of Fair Value, Fair Value Disclosure [Member] Senior notes
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Notes Payable, Fair Value Disclosure																	$ 35,000,000	$ 35,900,000	$ 36,500,000
Accumlated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance			10,643,000		11,933,000	12,784,000	11,379,000	9,994,000	(2,216,000)	(2,141,000)	(2,068,000)	(2,700,000)	9,717,000	10,643,000	9,311,000	7,294,000
Other comprehensive income before reclassifications					(4,994,000)	(851,000)	(612,000)	1,385,000	0	0	0	0	(4,994,000)	(851,000)	(612,000)	1,385,000
Amounts reclassified from AOCI to income tax expense (benefit) in the Condensed Consolidated Statements of Income						0		0		(75,000)		632,000		(75,000)		632,000
Total other comprehensive income (loss), net of tax	(4,994,000)	(612,000)	(5,920,000)	1,405,000		(851,000)		1,385,000		(75,000)		632,000		(926,000)		2,017,000
Ending balance	$ 4,723,000		$ 4,723,000		$ 6,939,000	$ 11,933,000	$ 10,767,000	$ 11,379,000	$ (2,216,000)	$ (2,216,000)	$ (2,068,000)	$ (2,068,000)	$ 4,723,000	$ 9,717,000	$ 8,699,000	$ 9,311,000