Commitments and Contingencies (Narrative) (Details) $ in Millions		1 Months Ended	12 Months Ended
	Mar. 20, 2014 USD ($)	Mar. 31, 2012 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2009 USD ($) room	Sep. 30, 2018 USD ($)	May 17, 2017 USD ($)	Jul. 31, 2014 USD ($)	May 31, 2012 USD ($)	Sep. 30, 2011 USD ($)	Jul. 31, 2010 USD ($)	May 31, 2010 USD ($)	Jun. 30, 2009 USD ($)	Feb. 28, 2006 USD ($)
Long Island Expressway/Cross Island Parkway Matter [Member]
Loss Contingencies [Line Items]
Estimated value of project completed in Feb. 2006													$ 130.0
Value of claim filed		$ 50.7
Amount receivable as per final agreement									$ 0.5
Value of counterclaim filed								$ 151.0
Fontainebleau Matter [Member]
Loss Contingencies [Line Items]
Number of rooms in hotel/casino complex | room				3,800
Amount of court order in favor of plaintiff											$ 45.0
Total outstanding liens on property, including subcontractors' liens												$ 44.0
Amount set aside from approved sale for distribution to satisfy creditor claims										$ 125.0
Estimated sustainable lien amount										$ 350.0
Westgate Planet Hollywood Matter [Member]
Loss Contingencies [Line Items]
Settlement receipt			$ 16.0
Total awards	$ 19.7
Damages awarded which were anticipated to be paid including interest	$ 3.1
Value of cross complaint filed				$ 51.0
Value of counterclaim filed				45.0
Total outstanding liens on property, including subcontractors' liens				23.2
Value of mechanic's lien release bond				$ 22.3			$ 22.3
Value of supersedeas bond							1.7
Total value of security							$ 24.0
Total value of security, interest and fees					$ 4.0
Minimum [Member[ | Westgate Planet Hollywood Matter [Member]
Loss Contingencies [Line Items]
Total value of security						$ 20.0