EMPLOYEE BENEFIT PLANS (Tables)

6 Months Ended

Jun. 30, 2017

Pension and Other Postretirement Benefits Cost (Reversal of Cost) [Abstract]

Components of the Net Periodic Benefit Cost

Components of the net periodic benefit cost of PLC's defined benefit pension plan for the three and six months ended June 30, 2017 and 2016, are as follows: 

	For The Three Months Ended June 30,										For The Six Months Ended June 30,
	2017					2016					2017					2016
	Defined Benefit Pension Plan			Excess Benefit Plan		Defined Benefit Pension Plan			Excess Benefit Plan		Defined Benefit Pension Plan			Excess Benefit Plan		Defined Benefit Pension Plan			Excess Benefit Plan
	(Dollars In Thousands)
Service cost — benefits earned during the period	$	3,348		$	334	$	2,906		$	478	$	6,696		$	668	$	5,812		$	791
Interest cost on projected benefit obligation	2,191			297		2,737			317		4,382			594		5,474			755
Expected return on plan assets	(3,352		)	—		(3,605		)	—		(6,704		)	—		(7,211		)	—
Amortization of prior service cost	—			—		—			—		—			—		—			—
Amortization of actuarial losses	—			118		—			50		—			236		—			50
Preliminary net periodic benefit cost	2,187			749		2,038			845		4,374			1,498		4,075			1,596
Settlement/curtailment expense	—			—		—			1,500		—			—		—			1,500
Total net periodic benefit costs	$	2,187		$	749	$	2,038		$	2,345	$	4,374		$	1,498	$	4,075		$	3,096