Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2016	Nov. 30, 2015	Nov. 30, 2014
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 7.0	$ 18.0	$ (16.2)	$ (50.0)
Other comprehensive income (loss):
Amortization of net actuarial losses, net of $23.2 million, $31.3 million, $20.4 million, and $1.7 million of income taxes in fiscal 2016, 2015, 2014, and one month ended December 31, 2015, respectively	3.4	37.1	49.4	31.1
Actuarial gains (losses), net of $4.8 million, $36.9 million, $89.8 million and $4.6 million of income taxes in fiscal 2016, 2015, 2014, and one month ended December 31, 2015, respectively	(8.6)	7.5	(56.6)	(136.0)
Amortization of prior service credits, net of $0.4 million, $0.4 million, $0.4 million, and $0.0 million of income taxes in fiscal 2016, 2015, 2014, and one month ended December 31, 2015, respectively	(0.1)	(0.6)	(0.8)	(0.5)
Comprehensive income (loss)	$ 1.7	$ 62.0	$ (24.2)	$ (155.4)