Fair Value Measurements (Supply Commitment) (Details) $ in Thousands	Dec. 31, 2015 USD ($)
Supply Commitment [Line Items]
Outstanding financial letters of credit	$ 8,178
Less than one year [Member]
Supply Commitment [Line Items]
Outstanding financial letters of credit	2,694
More than one year to five years [Member]
Supply Commitment [Line Items]
Outstanding financial letters of credit	5,124
Over five years [Member]
Supply Commitment [Line Items]
Outstanding financial letters of credit	360
Secured [Member]
Supply Commitment [Line Items]
Outstanding financial letters of credit	7,891
Secured [Member] | Less than one year [Member]
Supply Commitment [Line Items]
Outstanding financial letters of credit	2,458
Secured [Member] | More than one year to five years [Member]
Supply Commitment [Line Items]
Outstanding financial letters of credit	5,073
Secured [Member] | Over five years [Member]
Supply Commitment [Line Items]
Outstanding financial letters of credit	360
Secured by Collateral [Member]
Supply Commitment [Line Items]
Outstanding financial letters of credit	7,073
Secured by Collateral [Member] | Less than one year [Member]
Supply Commitment [Line Items]
Outstanding financial letters of credit	1,658
Secured by Collateral [Member] | More than one year to five years [Member]
Supply Commitment [Line Items]
Outstanding financial letters of credit	5,055
Secured by Collateral [Member] | Over five years [Member]
Supply Commitment [Line Items]
Outstanding financial letters of credit	360
Secured by Bank Lines of Credit [Member]
Supply Commitment [Line Items]
Outstanding financial letters of credit	818
Secured by Bank Lines of Credit [Member] | Less than one year [Member]
Supply Commitment [Line Items]
Outstanding financial letters of credit	800
Secured by Bank Lines of Credit [Member] | More than one year to five years [Member]
Supply Commitment [Line Items]
Outstanding financial letters of credit	18
Unsecured [Member]
Supply Commitment [Line Items]
Outstanding financial letters of credit	287
Unsecured [Member] | Less than one year [Member]
Supply Commitment [Line Items]
Outstanding financial letters of credit	236
Unsecured [Member] | More than one year to five years [Member]
Supply Commitment [Line Items]
Outstanding financial letters of credit	$ 51