Benefit Plans and Other Postretirement Benefits, Defined benefit plans (Details) - Pension Benefits - USD ($)	1 Months Ended	3 Months Ended		9 Months Ended
	Jan. 31, 2018	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Components of net pension expense:
Service cost		$ 2,000,000.0	$ 1,800,000	$ 5,500,000	$ 5,600,000
Interest cost		5,400,000	4,900,000	16,200,000	14,700,000
Expected return on plan assets		(9,200,000)	(9,600,000)	(27,800,000)	(28,900,000)
Amortization of prior service cost		400,000	600,000	1,300,000	1,800,000
Amortization of net actuarial losses		4,600,000	5,800,000	13,900,000	17,500,000
Net pension expense		3,200,000	$ 3,500,000	9,100,000	$ 10,700,000
United States
Defined Benefit Plan Disclosure
Estimated future employer contribution in fiscal year		$ 0		$ 0
Employer contributions	$ 81,000,000.0