Description Of The Business And Summary Of Significant Accounting Policies Description Of The Business And Summary Of Significant Accounting Policies (Reconciliation Of Net Income Attributable To Ensco Shares Used In Basic And Diluted EPS Computations) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Accounting Policies [Abstract]
Income (loss) from continuing operations attributable to Ensco	$ 882.1	$ (1,466.1)	$ (2,703.1)
Income from continuing operations allocated to non-vested share awards	16.6	2.0	7.9
Income (Loss) from Continuing Operations Attributable to Parent, Available to Common Stockholders	$ 865.5	$ (1,468.1)	$ (2,711.0)

Description Of The Business And Summary Of Significant Accounting Policies Description Of The Business And Summary Of Significant Accounting Policies (Reconciliation Of Net Income Attributable To Ensco Shares Used In Basic And Diluted EPS Computations) (Details) - USD ($)
$ in Millions

12 Months Ended

Dec. 31, 2016

Dec. 31, 2015

Dec. 31, 2014

Accounting Policies [Abstract]

Income (loss) from continuing operations attributable to Ensco

$ 882.1

$ (1,466.1)

$ (2,703.1)

Income from continuing operations allocated to non-vested share awards

16.6

2.0

7.9

Income (Loss) from Continuing Operations Attributable to Parent, Available to Common Stockholders

$ 865.5

$ (1,468.1)

$ (2,711.0)