Employee Benefits Plans (Details Textual)	12 Months Ended
	Dec. 31, 2017 USD ($) Age	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2013 Age	Dec. 31, 2018 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Accrued pension liability	$ 416,280,000	$ 455,736,000
One-time Non-cash Charge	8,000,000
Pension plans, accumulated other comprehensive income (loss)	13,000,000
Pension annuity settlement	(5,454,000)	(7,650,000)	$ 509,000
Expense related to defined contribution savings plans	39,000,000	38,000,000	$ 38
Deferred compensation	62,680,000	49,533,000
Non-qualified supplemental pension plan
Defined Benefit Plan Disclosure [Line Items]
Accrued pension liability	55,000,000	53,000,000
Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Payment for settlement	71,299,000	0
Pension annuity settlement	(66,423,000)	0
Required pension contributions to our pension plans	$ 34,000,000
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Maximum age limit of qualified retirees for health care benefits | Age	65
Modified age limit of qualified retirees for health care benefits | Age				52
Modified years of service required for qualified retirees for health care benefits				12 years
United States
Defined Benefit Plan Disclosure [Line Items]
U.S. pension plan assets percentage of total pension plan assets	72.00%
Scenario, Forecast | Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss to be recognized					$ (29,000,000)
Scenario, Forecast | Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss to be recognized					$ 1,000,000
Rabbi Trusts [Member] | Deferred Compensation Arrangement with Individual, by Type of Compensation, Pension and Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Assets held in trust	$ 63,000,000	50,000,000
Value of common stock issued in trust	$ 2,000,000	$ 2,000,000