Equity Investments (Schedule of Financial Information Related to Unconsolidated Entities) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Equity Investments [Abstract]
Revenues	$ 294,461	$ 299,099	$ 926,886	$ 927,392
Operating costs and expenses	266,012	267,857	817,572	802,870
Income from continuing operations before taxes	$ 28,421	$ 31,211	$ 109,238	$ 124,447