Fair Value (Carrying Value And Estimated Fair Value Of Financial Instruments) (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2013 Carrying Value [Member] Level 2 [Member]	Dec. 31, 2012 Carrying Value [Member] Level 2 [Member]	Jun. 30, 2013 Carrying Value [Member] Level 3 [Member]	Dec. 31, 2012 Carrying Value [Member] Level 3 [Member]	Jun. 30, 2013 Carrying Value [Member] Level 3 [Member] Affiliated Entity [Member]	Dec. 31, 2012 Carrying Value [Member] Level 3 [Member] Affiliated Entity [Member]	Jun. 30, 2013 Carrying Value [Member] Level 3 [Member] Nonrecourse Long-Term Debt [Member]	Dec. 31, 2012 Carrying Value [Member] Level 3 [Member] Nonrecourse Long-Term Debt [Member]	Jun. 30, 2013 Estimated Fair Value [Member] Level 2 [Member]	Dec. 31, 2012 Estimated Fair Value [Member] Level 2 [Member]	Jun. 30, 2013 Estimated Fair Value [Member] Level 3 [Member]	Dec. 31, 2012 Estimated Fair Value [Member] Level 3 [Member]	Jun. 30, 2013 Estimated Fair Value [Member] Level 3 [Member] Affiliated Entity [Member]	Dec. 31, 2012 Estimated Fair Value [Member] Level 3 [Member] Affiliated Entity [Member]	Jun. 30, 2013 Estimated Fair Value [Member] Level 3 [Member] Nonrecourse Long-Term Debt [Member]	Dec. 31, 2012 Estimated Fair Value [Member] Level 3 [Member] Nonrecourse Long-Term Debt [Member]
Fair Value and Carrying Value, by Balance Sheet Grouping [Line Items]
Document Period End Date	Jun. 30, 2013
Long-term debt		$ 951,000	$ 951,000	$ 302,000	$ 302,000	$ 51,547	$ 51,547	$ 25,474	$ 32,803	$ 1,092,485	$ 1,164,639	$ 293,341	$ 320,892	$ 36,923	$ 43,686	$ 27,058	$ 35,297