Financial Statements for Guarantors of the Senior Notes (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Condensed Income Statements, Captions [Line Items]
Revenue	$ 1,676.8	$ 1,485.3	$ 3,303.5	$ 2,945.8
Cost of revenues	1,219.6	1,098.3	2,430.7	2,172.3
Selling, engineering, and administrative expenses	114.4	96.4	212.7	180.0
Gains on dispositions of property	40.1	11.4	55.9	99.8
Cost of revenues and operating costs	1,293.9	1,183.3	2,587.5	2,252.5
Operating profit (loss)	382.9	302.0	716.0	693.3
Other (income) expense	49.4	45.0	98.1	90.8
Equity in earnings of subsidiaries, net of taxes	0.0	0.0	0.0	0.0
Income before income taxes	333.5	257.0	617.9	602.5
Provision (benefit) for income taxes	112.7	83.9	208.1	196.4
Net income	220.8	173.1	409.8	406.1
Net income attributable to noncontrolling interest	8.8	8.9	17.6	15.5
Net income attributable to controlling interest	212.0	164.2	392.2	390.6
Other comprehensive income (loss)	4.6	3.8	5.1	7.1
Comprehensive income	225.4	176.9	414.9	413.2
Comprehensive income attributable to noncontrolling interest	9.7	9.5	19.1	16.8
Comprehensive income attributable to controlling interest	215.7	167.4	395.8	396.4
Parent
Condensed Income Statements, Captions [Line Items]
Revenue	0.0	0.0	0.0	0.0
Cost of revenues	(1.1)	(0.4)	(1.9)	0.0
Selling, engineering, and administrative expenses	30.8	28.1	56.2	50.1
Gains on dispositions of property	1.4	0.1	1.6	(0.1)
Cost of revenues and operating costs	28.3	27.6	52.7	50.2
Operating profit (loss)	(28.3)	(27.6)	(52.7)	(50.2)
Other (income) expense	2.7	4.5	7.1	8.2
Equity in earnings of subsidiaries, net of taxes	246.3	150.1	443.2	402.3
Income before income taxes	215.3	118.0	383.4	343.9
Provision (benefit) for income taxes	3.3	(46.2)	(8.8)	(46.7)
Net income	212.0	164.2	392.2	390.6
Net income attributable to noncontrolling interest	0.0	0.0	0.0	0.0
Net income attributable to controlling interest	212.0	164.2	392.2	390.6
Other comprehensive income (loss)	2.0	0.5	1.0	1.1
Comprehensive income	214.0	164.7	393.2	391.7
Comprehensive income attributable to noncontrolling interest	0.0	0.0	0.0	0.0
Comprehensive income attributable to controlling interest	214.0	164.7	393.2	391.7
Combined Guarantor Subsidiaries
Condensed Income Statements, Captions [Line Items]
Revenue	1,215.0	991.5	2,400.0	2,007.6
Cost of revenues	945.1	767.1	1,889.2	1,521.2
Selling, engineering, and administrative expenses	38.1	28.5	71.1	50.7
Gains on dispositions of property	7.9	7.0	7.8	41.3
Cost of revenues and operating costs	975.3	788.6	1,952.5	1,530.6
Operating profit (loss)	239.7	202.9	447.5	477.0
Other (income) expense	9.1	3.2	16.0	7.5
Equity in earnings of subsidiaries, net of taxes	66.8	27.3	124.6	76.4
Income before income taxes	297.4	227.0	556.1	545.9
Provision (benefit) for income taxes	92.2	110.6	180.1	214.4
Net income	205.2	116.4	376.0	331.5
Net income attributable to noncontrolling interest	0.0	0.0	0.0	0.0
Net income attributable to controlling interest	205.2	116.4	376.0	331.5
Other comprehensive income (loss)	0.0	0.0	(0.5)	0.0
Comprehensive income	205.2	116.4	375.5	331.5
Comprehensive income attributable to noncontrolling interest	0.0	0.0	0.0	0.0
Comprehensive income attributable to controlling interest	205.2	116.4	375.5	331.5
Combined Non-Guarantor Subsidiaries
Condensed Income Statements, Captions [Line Items]
Revenue	701.0	681.4	1,371.4	1,303.3
Cost of revenues	522.0	521.5	1,021.3	1,015.5
Selling, engineering, and administrative expenses	45.5	39.8	85.4	79.2
Gains on dispositions of property	30.8	4.3	46.5	58.6
Cost of revenues and operating costs	536.7	557.0	1,060.2	1,036.1
Operating profit (loss)	164.3	124.4	311.2	267.2
Other (income) expense	37.6	37.3	75.0	75.1
Equity in earnings of subsidiaries, net of taxes	0.0	0.0	0.0	0.0
Income before income taxes	126.7	87.1	236.2	192.1
Provision (benefit) for income taxes	14.6	25.6	33.2	37.1
Net income	112.1	61.5	203.0	155.0
Net income attributable to noncontrolling interest	0.0	0.0	0.0	0.0
Net income attributable to controlling interest	112.1	61.5	203.0	155.0
Other comprehensive income (loss)	2.6	3.3	4.6	6.0
Comprehensive income	114.7	64.8	207.6	161.0
Comprehensive income attributable to noncontrolling interest	0.0	0.0	0.0	0.0
Comprehensive income attributable to controlling interest	114.7	64.8	207.6	161.0
Eliminations
Condensed Income Statements, Captions [Line Items]
Revenue	(239.2)	(187.6)	(467.9)	(365.1)
Cost of revenues	(246.4)	(189.9)	(477.9)	(364.4)
Selling, engineering, and administrative expenses	0.0	0.0	0.0	0.0
Gains on dispositions of property	0.0	0.0	0.0	0.0
Cost of revenues and operating costs	(246.4)	(189.9)	(477.9)	(364.4)
Operating profit (loss)	7.2	2.3	10.0	(0.7)
Other (income) expense	0.0	0.0	0.0	0.0
Equity in earnings of subsidiaries, net of taxes	(313.1)	(177.4)	(567.8)	(478.7)
Income before income taxes	(305.9)	(175.1)	(557.8)	(479.4)
Provision (benefit) for income taxes	2.6	(6.1)	3.6	(8.4)
Net income	(308.5)	(169.0)	(561.4)	(471.0)
Net income attributable to noncontrolling interest	8.8	8.9	17.6	15.5
Net income attributable to controlling interest	(317.3)	(177.9)	(579.0)	(486.5)
Other comprehensive income (loss)	0.0	0.0	0.0	0.0
Comprehensive income	(308.5)	(169.0)	(561.4)	(471.0)
Comprehensive income attributable to noncontrolling interest	9.7	9.5	19.1	16.8
Comprehensive income attributable to controlling interest	$ (318.2)	$ (178.5)	$ (580.5)	$ (487.8)