Non-operating Income (Expense) (Tables)

12 Months Ended

Dec. 31, 2016

Nonoperating Income (Expense) [Abstract]

Schedule of Other Nonoperating Income (Expense) [Table Text Block]

	Year ended December 31,
Dollar amounts in millions	2016			2015			2014
Interest expense	$	(32.9	)	$	(32.0	)	$	(29.9	)
Amortization of debt charges	(1.1		)	(1.1		)	(1.2		)
Capitalized interest	1.9			1.9			1.3
Interest expense, net of capitalized interest	(32.1		)	(31.2		)	(29.8		)
Investment income	8.0			4.9			5.5
SERP market adjustments	0.2			(0.5		)	—
Investment income	8.2			4.4			5.5
Foreign currency losses	2.1			(5.3		)	(3.1		)
Early debt extinguishment	(17.3		)	—			—
Other non-operating income (expense)	(15.2		)	(5.3		)	(3.1		)
Total non-operating income (expense)	$	(39.1	)	$	(32.1	)	$	(27.4	)