Employee Benefit Plans (Tables)

3 Months Ended

Mar. 31, 2019

BancShares Plan

Defined Benefit Plan Disclosure [Line Items]

Schedule of Net Benefit Costs

BancShares Plan

For the three months endedMarch 31, 2019 and 2018, the components of net periodic benefit cost are as follows:

	Three months ended March 31
(Dollars in thousands)	2019			2018
Service cost	$	2,568		$	3,429
Interest cost	7,531			7,057
Expected return on assets	(12,867		)	(11,957		)
Amortization of prior service cost	14			20
Amortization of net actuarial loss	2,114			3,246
Net periodic (benefit) cost	$	(640	)	$	1,795

Bancorporation Plan

Defined Benefit Plan Disclosure [Line Items]

Schedule of Net Benefit Costs

Bancorporation Plan

For the three months endedMarch 31, 2019 and 2018, the components of net periodic benefit cost are as follows:

	Three months ended March 31
(Dollars in thousands)	2019			2018
Service cost	$	545		$	662
Interest cost	1,760			1,587
Expected return on assets	(2,768		)	(3,106		)
Amortization of net actuarial loss	627			71
Net periodic cost (benefit)	$	164		$	(786	)