Fair Value Measurements (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Total [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment in associated company	$ 19,606	$ 17,229
Total [Member] | Commodity Contracts on Precious Metal [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commodity contracts on precious metal and derivative features of Subordinated Notes	88	100
Total [Member] | Interest Rate Swap [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commodity contracts on precious metal and derivative features of Subordinated Notes	(277)
Total [Member] | Derivative Features of Subordinated Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commodity contracts on precious metal and derivative features of Subordinated Notes		793
Recurring [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment in associated company	19,606	17,229
Recurring [Member] | Level 1 [Member] | Commodity Contracts on Precious Metal [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commodity contracts on precious metal and derivative features of Subordinated Notes	88	127
Recurring [Member] | Level 1 [Member] | Interest Rate Swap [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commodity contracts on precious metal and derivative features of Subordinated Notes	0
Recurring [Member] | Level 1 [Member] | Derivative Features of Subordinated Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commodity contracts on precious metal and derivative features of Subordinated Notes		0
Recurring [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment in associated company	0	0
Recurring [Member] | Level 2 [Member] | Commodity Contracts on Precious Metal [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commodity contracts on precious metal and derivative features of Subordinated Notes	0	(27)
Recurring [Member] | Level 2 [Member] | Interest Rate Swap [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commodity contracts on precious metal and derivative features of Subordinated Notes	(277)
Recurring [Member] | Level 2 [Member] | Derivative Features of Subordinated Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commodity contracts on precious metal and derivative features of Subordinated Notes		0
Recurring [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment in associated company	0	0
Recurring [Member] | Level 3 [Member] | Commodity Contracts on Precious Metal [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commodity contracts on precious metal and derivative features of Subordinated Notes	0	0
Recurring [Member] | Level 3 [Member] | Interest Rate Swap [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commodity contracts on precious metal and derivative features of Subordinated Notes	0
Recurring [Member] | Level 3 [Member] | Derivative Features of Subordinated Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commodity contracts on precious metal and derivative features of Subordinated Notes		$ 793