Employee Benefit Plans (Tables)

3 Months Ended

Mar. 31, 2017

BancShares Plan

Defined Benefit Plan Disclosure [Line Items]

Schedule of Net Benefit Costs

BancShares Plan

For the three months ended March 31, 2017 and 2016, the components of net periodic benefit cost are as follows:

	Three months ended March 31
(Dollars in thousands)	2017			2016
Service cost	$	3,376		$	3,220
Interest cost	7,380			7,180
Expected return on assets	(10,698		)	(9,159		)
Amortization of prior service cost	52			52
Amortization of net actuarial loss	2,234			1,600
Net periodic benefit cost	$	2,344		$	2,893

Bancorporation Plan

Defined Benefit Plan Disclosure [Line Items]

Schedule of Net Benefit Costs

Bancorporation Plan

For the three months ended March 31, 2017 and 2016, the components of net periodic benefit cost are as follows:

	Three months ended March 31
(Dollars in thousands)	2017			2016
Service cost	$	671		$	650
Interest cost	1,683			1,675
Expected return on assets	(2,796		)	(2,779		)
Amortization of net actuarial loss	214			—
Net periodic benefit cost	$	(228	)	$	(454	)