Acquisitions and Divestitures (Details) (USD $) In Millions, unless otherwise specified	1 Months Ended	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Acquisitions:
Purchase price		$ 7.7	$ 29.6	$ 125.3	$ 83.4
Net cash paid		6.2	28.1	118.8	37.2
Goodwill recorded		5.1	7.0	87.2	9.5
Divestitures:
Proceeds		0	0	0	35.6
Gain recognized		0	0.1	0	12.5
Goodwill charged off		0	0	0	4.8
Expected purchase price for Meyer Steel Structures	$ 600
Energy Equipment Group
Divestitures:
Number of businesses acquired				3
Construction Products Group
Divestitures:
Number of businesses acquired				1