Employee Retirement Plans (Details Textual)	12 Months Ended
	Dec. 31, 2016 USD ($) portfolio	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Schedule of Benefit Plans Disclosures [Line Items]
Plan assets expected to be returned	$ 0
Unrecognized actuarial losses included in AOCL	142,800,000
Unrecognized actuarial losses included in AOCL, net of tax	89,700,000
Actuarial losses expected to be recognized in net periodic pension cost within twelve months	5,000,000
Actuarial losses expected to be recognized in net periodic pension cost within twelve months, net of tax	$ 3,100,000
Pension plan assets, number of portfolios | portfolio	2
Funding percentage	100.00%
Expected employer contributions to defined benefit plans next year	$ 2,500,000
Actual employer contributions to defined benefit plans	4,700,000	$ 16,200,000
Expected employer contributions to 401(k) plans and Supplemental Profit Sharing Plan next year	15,200,000
Actual employer contributions to 401(k) plans and Supplemental Profit Sharing Plan	18,500,000
Multiemployer plan, expected contributions in following year	2,300,000
Multiemployer plan contributions	$ 2,300,000	$ 2,500,000	$ 600,000
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's contributions to multiemployer plan as a percentage of total contributions (less than)	5.00%
Company contributions to the Profit Sharing Plan as a percentage of eligible compensation based on service	3.00%
Liability hedging portfolio
Schedule of Benefit Plans Disclosures [Line Items]
Funding percentage	110.00%
Liability hedging portfolio | Minimum
Schedule of Benefit Plans Disclosures [Line Items]
Target Allocation	50.00%
Liability hedging portfolio | Maximum
Schedule of Benefit Plans Disclosures [Line Items]
Target Allocation	100.00%
Growth portfolio | Maximum
Schedule of Benefit Plans Disclosures [Line Items]
Target Allocation	50.00%