Debt (Details 2) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Summary of short-term lines of credit
Outstanding	$ 38,200
Available	262,700
Short-term Debt [Member]
Summary of short-term lines of credit
Total	311,500	315,300
Outstanding	48,850	40,397
Available	262,650	274,903
Domestic [Member] | Short-term Debt [Member]
Summary of short-term lines of credit
Total	256,799	262,724
Outstanding	8,000	3,200
Available	248,799	259,524
Foreign [Member] | Short-term Debt [Member]
Summary of short-term lines of credit
Total	15,266	16,149
Outstanding	1,415	770
Available	13,851	15,379
Precious metal [Member] | Short-term Debt [Member]
Summary of short-term lines of credit
Total	39,435	36,427
Outstanding	39,435	36,427
Available	$ 0	$ 0