Business Segment Information - Information by Segment (Details) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016 USD ($)	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Sep. 30, 2015 USD ($)	Jun. 30, 2015 USD ($)	Mar. 31, 2015 USD ($)	Dec. 31, 2016 USD ($) segment	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Business segment information
Number of reportable segments | segment									2
Total revenue	$ 470.3	$ 393.9	$ 371.7	$ 375.4	$ 478.2	$ 396.1	$ 396.0	$ 353.5	$ 1,611.3	$ 1,623.8	$ 1,808.9
Total operating income	76.9	$ 45.9	20.4	$ 34.0	70.7	28.2	31.6	$ 15.2	177.2	145.7	105.4
Impairment of assets	0.1		$ 0.7		0.3	$ 2.5	$ 1.8		0.8	4.6	11.5
Total assets	1,808.4				1,730.0				1,808.4	1,730.0
Total capital expenditures									37.1	34.2	33.8
Total depreciation and amortization									54.3	53.3	59.7
Eliminations
Business segment information
Total revenue									(11.5)	(9.1)	(18.6)
Corporate, eliminations and other
Business segment information
Total operating income									1.7	1.0	2.2
Total assets	(7.4)				(63.5)				(7.4)	(63.5)
BSI
Business segment information
Impairment of assets									0.8	4.6	6.4
Total capital expenditures									34.6	30.1	31.5
Total depreciation and amortization									51.3	50.5	55.1
BSI | Operating segments
Business segment information
Total revenue									1,492.6	1,499.2	1,674.6
Total operating income									168.9	133.2	99.8
Total assets	1,779.8				1,714.4				1,779.8	1,714.4
BEST
Business segment information
Impairment of assets											5.1
Total capital expenditures									2.5	4.1	2.3
Total depreciation and amortization									3.0	2.8	4.6
BEST | Operating segments
Business segment information
Total revenue									130.2	133.7	152.9
Total operating income									6.6	11.5	$ 3.4
Total assets	$ 36.0				$ 79.1				$ 36.0	$ 79.1