Business Segment Information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014 segment	Jun. 30, 2013	Dec. 31, 2013
Business Segment Information
Number of reporting segments			2
Revenue:
Total revenue	$ 457.4	$ 454.9	$ 881.1	$ 848.3
Operating Income:
Total operating income	35.4	43.5	56.0	55.7
Assets:
Total assets	2,003.9		2,003.9		1,988.3
Eliminations
Revenue:
Total revenue	(5.5)	(3.8)	(10.5)	(7.9)
Corporate, eliminations and other
Operating Income:
Total operating income	(0.2)	(2.7)	1.1	(2.0)
Assets:
Total assets	(80.7)		(80.7)		(83.5)
BSI | Operating segments
Revenue:
Total revenue	421.5	421.6	815.4	787.9
Operating Income:
Total operating income	31.2	39.6	47.7	50.2
Assets:
Total assets	1,946.0		1,946.0		1,925.3
BEST | Operating segments
Revenue:
Total revenue	41.4	37.1	76.2	68.3
Operating Income:
Total operating income	4.4	6.6	7.2	7.5
Assets:
Total assets	$ 138.6		$ 138.6		$ 146.5