Business Segment Information (Reconciliation Of Segment Margin To (Loss) Income Before Income Taxes) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Segment Reporting [Abstract]
Segment margin	$ 72,065	$ 60,252
Corporate general and administrative expenses	(10,837)	(8,621)
Depreciation Amortization And Impairment	15,053	14,779
Depreciation and amortization	(15,053)	(14,779)
Interest expense	(11,441)	(10,596)
Distributable cash from equity investees in excess of equity in earnings	(6,564)	(6,733)
Non-cash items not included in segment margin	(4,295)	1,324
Cash payments from direct financing leases in excess of earnings	(1,232)	(1,221)
Income before income taxes	$ 22,643	$ 19,626