Business Segment Information (Reconciliation Of Segment Margin To (Loss) Income Before Income Taxes) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Segment Reporting [Abstract]
Segment margin	$ 64,824	$ 65,929	$ 207,331	$ 189,012
Corporate general and administrative expenses	(11,113)	(9,428)	(32,255)	(26,756)
Depreciation and amortization	(16,066)	(14,838)	(46,789)	(45,447)
Interest expense	(12,587)	(9,873)	(36,282)	(30,697)
Distributable cash from equity investees in excess of equity in earnings	(5,204)	(5,613)	(16,659)	(19,098)
Non-cash items not included in segment margin	507	(2,222)	(2,828)	(2,475)
Cash payments from direct financing leases in excess of earnings	(1,291)	(1,278)	(3,786)	(3,748)
Income before income taxes	$ 19,070	$ 22,677	$ 68,732	$ 60,791