Employee Retirement Plans - Narrative (Details)	12 Months Ended
	Dec. 31, 2018 USD ($) portfolio	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Schedule of Benefit Plans Disclosures [Line Items]
Plan assets expected to be returned	$ 0
Unrecognized actuarial losses included in AOCL	140,400,000
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	2,562,000,000	$ 4,858,000,000	$ 4,311,100,000	$ 4,048,700,000
Actuarial losses expected to be recognized in net periodic pension cost within twelve months	1,100,000
Actuarial losses expected to be recognized in net periodic pension cost within twelve months, net of tax	$ 800,000
Pension plan assets, number of portfolios | portfolio	2
Target Allocation	100.00%
Expected employer contributions to defined benefit plans next year	$ 1,100,000
Actual employer contributions to defined benefit plans	31,600,000	2,500,000
Defined Benefit Plan, Plan Assets, Payment for Settlement	25,000,000
Expected employer contributions to 401(k) plans and Supplemental Profit Sharing Plan next year	10,800,000
Actual employer contributions to 401(k) plans and Supplemental Profit Sharing Plan	15,400,000
Defined Contribution Plan, Employer Contribution from Spin-Off	$ 5,900,000
Minimum
Schedule of Benefit Plans Disclosures [Line Items]
Company contributions to the Profit Sharing Plan as a percentage of eligible compensation based on service	1.00%
Maximum
Schedule of Benefit Plans Disclosures [Line Items]
Company contributions to the Profit Sharing Plan as a percentage of eligible compensation based on service	3.00%
Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Attributable to Parent [Member]
Schedule of Benefit Plans Disclosures [Line Items]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	$ (107,200,000)	$ (82,700,000)	$ (89,700,000)
Boilermaker-Blacksmith National Pension Trust [Member]
Schedule of Benefit Plans Disclosures [Line Items]
Entity Tax Identification Number	486168020