Business Segment Information (Reconciliation Of Segment Margin To (Loss) Income Before Income Taxes) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Segment Reporting [Abstract]
Segment margin	$ 262,333	[1]	$ 202,501	[1]	$ 149,564	[1]
Corporate general and administrative expenses	(38,372)		(31,685)		(110,058)
Depreciation, amortization and impairment	(61,166)		(62,190)		(53,569)
Interest expense	(40,921)		(35,767)		(22,924)
Distributable cash from equity investees in excess of equity in earnings	(24,464)		(16,681)		(2,284)
Non-cash items not included in segment margin	(5,280)		(1,531)		(4,479)
Cash payments from direct financing leases in excess of earnings	(5,016)		(4,615)		(4,203)
Income (loss) before income taxes	$ 87,114		$ 50,032		$ (47,953)

[1] A reconciliation of Segment Margin to income (loss) before income taxes for each year presented is as follows: Year Ended December 31, 2012 2011 2010Segment margin$262,333 $202,501 $149,564Corporate general and administrative expenses(38,372) (31,685) (110,058)Depreciation, amortization and impairment(61,166) (62,190) (53,569)Interest expense(40,921) (35,767) (22,924)Distributable cash from equity investees in excess of equity in earnings(24,464) (16,681) (2,284)Non-cash items not included in segment margin(5,280) (1,531) (4,479)Cash payments from direct financing leases in excess of earnings(5,016) (4,615) (4,203)Income (loss) before income taxes$87,114 $50,032 $(47,953)