CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
COMPREHENSIVE INCOME:
Net income	$ 732.4	$ 778.8	$ 741.1
Other comprehensive income (loss) net of tax:
Decrease (increase) in pension and other post-retirement benefits (net of income tax of $(1.6), $2.6 and $2.6, respectively)	2.6	(3.5)	(3.7)
Foreign currency translation adjustments	0.3
Total other comprehensive income (loss)	2.9	(3.5)	(3.7)
Total comprehensive income	735.3	775.3	737.4
Comprehensive income attributable to the non-controlling interest	3.9	2.3	4.7
Comprehensive income attributable to SCC	$ 731.4	$ 773.0	$ 732.7