Commitments And Contingencies (Funding Commitments By Third Parties Or Contingent Events) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012
Recorded Unconditional Purchase Obligation [Line Items]
Total Amounts Committed	$ 132,011
Less Than 1 Year	116,091
1 - 3 Years	15,779
3 - 5 Years	141
More Than 5 Years	0
Letters Of Credit And Surety Bonds [Member]
Recorded Unconditional Purchase Obligation [Line Items]
Total Amounts Committed	32,674
Less Than 1 Year	32,624
1 - 3 Years	50
3 - 5 Years	0
More Than 5 Years	0
Purchase Obligations [Member]
Recorded Unconditional Purchase Obligation [Line Items]
Total Amounts Committed	99,337
Less Than 1 Year	83,467
1 - 3 Years	15,729
3 - 5 Years	141
More Than 5 Years	$ 0