Consolidation of Certain Interests (Narrative) (Details) (USD $) In Millions, unless otherwise specified	0 Months Ended
	Aug. 06, 2010 Borgata	Jun. 30, 2012 LVE	Jun. 30, 2012 Amended Borgata	Mar. 17, 2010 Maximum Borgata	Jun. 30, 2012 Maximum Amended Borgata	Jan. 31, 2010 Borgata Hotel Casino and Spa
Consolidated Entities [Line Items]
Equity method investment, ownership percentage						50.00%
Proceeds of one-time distribution from subsidiary, including priority distribution	$ 135.4
Proceeds of priority distribution for excess prior capital contributions to parent	$ 30.8
Sale of joint venture partner interest under regulatory settlement, time period from agreement until sale				30 months	48 months
Sale of joint venture partner interest under regulatory settlement, initial time period under which joint venture partner controls decision to sell			36 months	18 months
Sale of joint venture partner interest under regulatory settlement, increase in time period from agreement until sale			18 months
Sale of joint venture partner interest under regulatory settlement, time period before end of agreement during which divestiture trust controls decision to sell			12 months
Term of unrecorded commitment under energy and sales agreement		25 years