Consolidated Statements of Partners' and Owners' Capital (Deficit) (USD $) In Thousands, unless otherwise specified	Total	Common Unitholders	Class B Unitholders	Subordinated Unitholders	General Partner Interest	Accumulated Other Comprehensive Loss [Member]
Accumulated Other Comprehensive Loss at Dec. 31, 2012	$ (27,240)					$ (27,240)
General Partners' Capital Account at Dec. 31, 2012	29,496				29,496
Total Partners' Capital at Dec. 31, 2012	1,362,808
Limited Partners' Capital Account at Dec. 31, 2012	(37,342)		(37,342)
Common Unitholders Equity at Dec. 31, 2012	448,412	448,412
Subordinated Unitholders Equity at Dec. 31, 2012	949,482			949,482
Increase (Decrease) in Stockholders' Equity
Net loss	(42,487)	(10,331)	0	(30,707)	(1,449)	0
Sale of common and general partner units	372,289	364,840	0	0	7,449	0
Distributions	(17,125)	(16,783)	0	0	(342)	0
Interest rate cash flow hedges	21,267	0	0	0	0	21,267
Accumulated Other Comprehensive Loss at Mar. 31, 2013	(5,973)
General Partners' Capital Account at Mar. 31, 2013	35,154				35,154
Total Partners' Capital at Mar. 31, 2013	1,696,752
Limited Partners' Capital Account at Mar. 31, 2013	(37,342)
Common Unitholders Equity at Mar. 31, 2013	786,138
Subordinated Unitholders Equity at Mar. 31, 2013	$ 918,775			$ 918,775