Employee Benefit Plans and Other Postretirement Benefits (Details) - USD ($)	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 6,100,000	$ 5,900,000
Interest cost	10,200,000	11,500,000
Expected return on plan assets	(12,400,000)	(13,300,000)
Net amortization of unrecognized amounts, Prior service cost	1,400,000	1,400,000
Net amortization of unrecognized amounts, Actuarial loss	1,400,000	2,100,000
Net periodic benefit cost	6,700,000	7,600,000
Pension Contributions [Abstract]
Contributions to pension plan	0	0
Expected contributions to pension plan	27,000,000
Postretirement Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	200,000	400,000
Interest cost	200,000	300,000
Net amortization of unrecognized amounts, Prior service cost	0	0
Net amortization of unrecognized amounts, Actuarial loss	(200,000)	100,000
Net periodic benefit cost	$ 200,000	$ 800,000