Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2017

Summary of Significant Accounting Policies [Abstract]

Supplemental Cash Flow Information [Table Text Block]

Supplemental cash flow information is shown in the table below:

	Year Ended December 31,
	2017			2016			2015
Supplemental Disclosures	(in millions)
Cash paid for interest, net of capitalized interest	$	134.9		$	139.1		$	139.4
Cash paid (refund received) for income taxes, net	$	(0.3	)	$	(123.5	)	$	487.8
Non-cash investing activities
Change in capital expenditure accrual balance	$	60.2		$	(32.8	)	$	(129.2	)

Property, Plant and Equipment [Table Text Block]

Buildings	10 to 30 years
Leasehold improvements	3 to 10 years
Service, transportation and field service equipment	3 to 7 years
Furniture and office equipment	3 to 7 years

Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]

The following is a reconciliation of the components of basic and diluted shares used in the EPS calculation:

	December 31,
	2017	2016	2015
	(in millions)
Weighted-average basic common shares outstanding	240.6	221.7	176.6
Potential number of shares issuable upon exercise of in-the-money stock options under the Long-Term Stock Incentive Plan	—	—	—
Average diluted common shares outstanding	240.6	221.7	176.6