Construction Joint Ventures - Schedule of Unconsolidated Construction Joint Ventures Assets and Liabilities (Parenthetical) (Details) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018	Jun. 30, 2018
Construction Joint Venture
Performance Guarantees	$ 88.7	$ 88.2	$ 88.6
Unconsolidated Joint Venture Back charges claims	12.8	15.6	10.6
Deficit in unconsolidated construction joint venture, including provisions for losses	58.7	11.5	14.7
Reporting Entitys Interest in Joint Venture [Member]
Construction Joint Venture
Affirmative Claim Recovery Estimate	$ 89.4	$ 78.1	$ 65.8