Pension and Other Postretirement Benefit Plans (Tables)

12 Months Ended

Dec. 31, 2018

Defined Contribution Plan [Abstract]

Schedule of Changes in Benefit Obligation, Plan Assets and Funded Status

The reconciliation of changes in the benefit obligation, plan assets and funded status of these plans at December 31, 2018 and 2017 is as follows:

	Pension Benefits						Other Postretirement Benefits
	at December 31,						at December 31,
	2018			2017			2018			2017
Change in benefit obligation:
Benefit obligation at beginning of period	$	733,990		$	735,177		$	591,563		$	700,085
Service cost	1,150			2,948			—			—
Interest cost	23,505			25,265			18,706			23,945
Actuarial (gain) loss	(60,351		)	35,281			(101,259		)	(101,379		)
Plan settlements	—			(29,142		)	—			—
Benefits and other payments	(54,152		)	(35,539		)	(35,419		)	(31,088		)
Benefit obligation at end of period	$	644,142		$	733,990		$	473,591		$	591,563
Change in plan assets:
Fair value of plan assets at beginning of period	$	679,245		$	632,434		$	—		$	—
Actual return on plan assets	(48,470		)	110,311			—			—
Company contributions	1,724			1,181			35,419			31,088
Benefits and other payments	(54,152		)	(35,539		)	(35,419		)	(31,088		)
Plan settlements	—			(29,142		)	—			—
Fair value of plan assets at end of period	$	578,347		$	679,245		$	—		$	—
Funded status:
Current liabilities	$	(1,623	)	$	(1,785	)	$	(32,345	)	$	(37,464	)
Noncurrent liabilities	(64,172		)	(52,960		)	(441,246		)	(554,099		)
Net obligation recognized	$	(65,795	)	$	(54,745	)	$	(473,591	)	$	(591,563	)
Amounts recognized in accumulated other comprehensive income consist of:
Net actuarial loss	$	263,229		$	243,456		$	184,438		$	301,901
Prior service credit	(367		)	(869		)	(23,354		)	(25,759		)
Net amount recognized (before tax effect)	$	262,862		$	242,587		$	161,084		$	276,142

The reconciliation of changes in the benefit obligation and funded status of these plans at December 31, 2018 and 2017 is as follows:

	CWP						Workers' Compensation
	at December 31,						at December 31,
	2018			2017			2018			2017
Change in benefit obligation:
Benefit obligation at beginning of period	$	162,840		$	118,836		$	78,528		$	78,099
State administrative fees and insurance bond premiums	—			—			2,671			3,198
Service cost	6,650			5,122			6,230			5,734
Interest cost	5,245			4,050			2,283			2,321
Actuarial loss (gain)	14,832			47,939			(5,134		)	3,553
Benefits paid	(12,379		)	(13,107		)	(13,592		)	(14,377		)
Benefit obligation at end of period	$	177,188		$	162,840		$	70,986		$	78,528
Funded status:
Current assets	$	—		$	—		$	1,384		$	1,437
Current liabilities	(12,187		)	(12,972		)	(12,628		)	(13,317		)
Noncurrent liabilities	(165,001		)	(149,868		)	(59,742		)	(66,648		)
Net obligation recognized	$	(177,188	)	$	(162,840	)	$	(70,986	)	$	(78,528	)
Amounts recognized in accumulated other comprehensive income consist of:
Net actuarial loss (gain)	$	8,542		$	(7,144	)	$	(13,561	)	$	(8,505	)
Net amount recognized (before tax effect)	$	8,542		$	(7,144	)	$	(13,561	)	$	(8,505	)

Schedule of Components of Net Periodic Benefit Costs

The components of net periodic benefit cost (credit) are as follows:

	Pension Benefits									Other Postretirement Benefits
	For the Years Ended December 31,									For the Years Ended December 31,
	2018			2017			2016			2018			2017			2016
Components of net periodic benefit cost (credit):
Service cost	$	1,150		$	2,948		$	1,533		$	—		$	—		$	—
Interest cost	23,505			25,265			25,048			18,706			23,945			24,241
Expected return on plan assets	(40,370		)	(42,383		)	(46,674		)	—			—			—
Amortization of prior service credits	(502		)	(502		)	(502		)	(2,405		)	(2,405		)	—
Recognized net actuarial loss	8,715			8,896			9,163			16,205			23,112			19,168
Settlement loss	—			10,153			22,196			—			—			—
Net periodic benefit (credit) cost	$	(7,502	)	$	4,377		$	10,764		$	32,506		$	44,652		$	43,409

The components of the net periodic cost are as follows:

	CWP									Workers’ Compensation
	For the Years Ended									For the Years Ended
	December 31,									December 31,
	2018			2017			2016			2018			2017			2016
Service cost	$	6,650		$	5,122		$	4,327		$	6,230		$	5,734		$	7,466
Interest cost	5,245			4,050			4,283			2,283			2,321			2,499
Recognized net actuarial gain	(853		)	(7,631		)	(4,948		)	(79		)	(598		)	(395		)
State administrative fees and insurance bond premiums	—			—			—			2,671			3,198			3,199
Curtailment gain	—			—			(1,307		)	—			—			—
Net periodic cost	$	11,042		$	1,541		$	2,355		$	11,105		$	10,655		$	12,769

Schedule of Amounts Included in Accumulated Other Comprehensive Loss to be Recognized over Next Fiscal Year

Amounts included in accumulated other comprehensive loss which are expected to be recognized in 2019 net periodic benefit costs:

				Other
	Pension			Postretirement
	Benefits			Benefits
Prior service credit recognition	$	(366	)	$	(2,405	)
Actuarial loss recognition	$	5,958		$	9,262

The following are amounts included in accumulated other comprehensive income that are expected to be recognized in 2019 net periodic benefit costs:

			Workers'
	CWP		Compensation
	Benefits		Benefits
Actuarial loss (gain) recognition	$	1,016	$	(774	)

Schedule of Pension Plans with an Accumulated Benefit Obligation in Excess of Plan Assets

The following table provides information related to pension plans with an accumulated benefit obligation in excess of plan assets:

	As of December 31,
	2018		2017
Projected benefit obligation	$	644,142	$	733,990
Accumulated benefit obligation	$	644,069	$	733,949
Fair value of plan assets	$	578,347	$	679,245

Schedule of Weighted-Average Assumptions Used

The weighted-average assumptions used to determine net periodic benefit costs are as follows:

	Pension Benefits						Other Postretirement Benefits
	For the Years Ended						For the Years Ended
	December 31,						December 31,
	2018		2017		2016		2018		2017		2016
Discount rate	3.69	%	4.27	%	4.52	%	3.65	%	4.22	%	4.50	%
Expected long-term return on plan assets	6.90	%	6.90	%	7.25	%	—		—		—
Rate of compensation increase	3.73	%	3.90	%	3.80	%	—		—		—

The weighted-average assumptions used to determine benefit obligations are as follows:

	Pension Benefits				Other Postretirement Benefits
	at December 31,				at December 31,
	2018		2017		2018		2017
Discount rate	4.34	%	3.65	%	4.34	%	3.65	%
Rate of compensation increase	3.73	%	3.73	%	—		—

The weighted-average discount rates used to determine benefit obligations and net periodic cost are as follows:

	CWP						Workers' Compensation
	For the Years Ended						For the Years Ended
	December 31,						December 31,
	2018		2017		2016		2018		2017		2016
Benefit obligations	4.42	%	3.75	%	4.40	%	4.26	%	3.57	%	4.05	%
Net periodic cost	3.75	%	4.40	%	4.60	%	3.57	%	4.05	%	4.26	%

Schedule of Health Care Cost Trend Rates

The assumed health care cost trend rates are as follows:

	At December 31,
	2018		2017
Health care cost trend rate for next year	5.83	%	6.06	%
Rate to which the cost trend is assumed to decline (ultimate trend rate)	4.50	%	4.50	%
Year that the rate reaches ultimate trend rate	2038		2038

Schedule of Effect of One-Percentage-Point Change in Assumed Health Care Cost Trend Rates

Assumed health care cost trend rates have a significant effect on the amounts reported for the medical plans. A one-percentage point change in assumed health care cost trend rates would have the following effects:

	1 Percentage		1 Percentage
	Point Increase		Point Decrease
Effect on total of service and interest cost components	$	2,618	$	(2,199	)
Effect on accumulated postretirement benefit obligation	$	52,312	$	(44,591	)

Schedule of Fair Value of Plan Assets

The fair values of plan assets at December 31, 2018 and 2017 by asset category are as follows:

	Fair Value Measurements at December 31, 2018								Fair Value Measurements at December 31, 2017
			Quoted								Quoted
			Prices in								Prices in
			Active								Active
			Markets for		Significant		Significant				Markets for		Significant		Significant
			Identical		Observable		Unobservable				Identical		Observable		Unobservable
			Assets		Inputs		Inputs				Assets		Inputs		Inputs
	Total		(Level 1)		(Level 2)		(Level 3)		Total		(Level 1)		(Level 2)		(Level 3)
Asset Category
Cash/Accrued Income	$	101	$	101	$	—	$	—	$	5,202	$	5,202	$	—	$	—
US Equities (a)	—		—		—		—		12		12		—		—
Mercer Common Collective Trusts (b)	578,246		—		—		—		674,031		—		—		—
Total	$	578,347	$	101	$	—	$	—	$	679,245	$	5,214	$	—	$	—

__________

(a) This category includes investments in US common stocks and corporate debt.

(b) Certain investments that are measured at fair value using the net asset value per share (or its equivalent) practical expedient have not been classified in the fair value hierarchy but are included in the total.

Schedule of Expected Benefit Payments

The following benefit payments, reflecting expected future service, are expected to be paid:

			Other
	Pension		Postretirement
	Benefits		Benefits
2019	$	43,588	$	32,345
2020	$	41,867	$	32,366
2021	$	41,421	$	32,152
2022	$	41,630	$	31,660
2023	$	41,374	$	31,112
Year 2024-2028	$	199,992	$	150,344

The following benefit payments, which reflect expected future claims as appropriate, are expected to be paid:

			Workers' Compensation
	CWP		Total		Actuarial		Other
	Benefits		Benefits		Benefits		Benefits
2019	$	12,187	$	13,987	$	11,244	$	2,743
2020	$	10,319	$	14,007	$	11,196	$	2,811
2021	$	9,753	$	13,800	$	10,918	$	2,882
2022	$	9,528	$	13,874	$	10,920	$	2,954
2023	$	9,633	$	13,766	$	10,738	$	3,028
Year 2024-2028	$	52,265	$	70,429	$	54,117	$	16,312