Business Segment Information (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2016 USD ($) segment	Sep. 30, 2015 USD ($)	Dec. 31, 2015 USD ($)
Business segment information
Number of reportable segments | segment			2
Revenue	$ 393.9	$ 396.1	$ 1,141.0	$ 1,145.6
Operating Income	45.9	28.2	100.3	75.0
Assets	1,797.9		1,797.9		$ 1,730.0
Eliminations
Business segment information
Revenue	(3.1)	(3.4)	(7.8)	(5.9)
Corporate, eliminations and other
Business segment information
Operating Income	(0.1)	(0.1)	0.9	0.7
Assets	(4.2)		(4.2)		(63.5)
BSI | Operating segments
Business segment information
Revenue	361.5	366.6	1,057.6	1,060.3
Operating Income	43.3	25.8	95.3	68.2
Assets	1,780.6		1,780.6		1,714.4
BEST | Operating segments
Business segment information
Revenue	35.5	32.9	91.2	91.2
Operating Income	2.7	$ 2.5	4.1	$ 6.1
Assets	$ 21.5		$ 21.5		$ 79.1