Commitments and Contingent Liabilities (Details) $ in Millions	6 Months Ended
	Jun. 30, 2017 USD ($) drilling_unit	Dec. 31, 2016 USD ($)
Long-term Purchase Commitment [Line Items]
IRS proposed unfavorable tax adjustments	$ 85.0
Gross unrecognized tax benefits	114.0	$ 120.0
Tax impact of net unrecognized tax benefits, if reversed	52.0
Letters of credit issued	15.1
Newbuild Jack-Up Rigs [Member]
Long-term Purchase Commitment [Line Items]
Long-term purchase commitment, amount	$ 1,250.0
Saudi Arabia Joint Venture [Member] | Maximum [Member]
Long-term Purchase Commitment [Line Items]
Number of drilling rigs to be purchased by joint venture | drilling_unit	20
Revolving Credit Facility [Member]
Long-term Purchase Commitment [Line Items]
Letters of credit issued	$ 5.1