Defined Benefit Pension Plans (Tables)

9 Months Ended

Sep. 30, 2016

Defined Benefit Pension Plans and Defined Benefit Postretirement Plans Disclosure [Abstract]

Components of Net Periodic Benefit Cost

The composition of net periodic benefit cost was as follows:

(Dollars in thousands)	Qualified Pension Plan												Non-Qualified Retirement Plans
	Three months						Nine months						Three months				Nine months
Periods ended September 30,	2016			2015			2016			2015			2016		2015		2016		2015
Net Periodic Benefit Cost:
Service cost		$537			$615			$1,611			$1,844			$30		$20		$91		$59
Interest cost	644			731			1,932			2,195			108		122		324		367
Expected return on plan assets	(1,158		)	(1,129		)	(3,475		)	(3,386		)	—		—		—		—
Amortization of prior service (credit) cost	(6		)	(6		)	(17		)	(17		)	—		—		—		—
Recognized net actuarial loss	207			313			621			937			62		61		185		183
Net periodic benefit cost		$224			$524			$672			$1,573			$200		$203		$600		$609

Schedule of Assumptions Used for Net Periodic Benefit Cost

The following table presents the measurement date and weighted-average assumptions used to determine net periodic benefit cost:

	Qualified Pension Plan		Non-Qualified Retirement Plans
Periods ended September 30,	2016	2015	2016	2015
Measurement date	Dec 31, 2015	Dec 31, 2014	Dec 31, 2015	Dec 31, 2014
Discount rate	N/A	4.125%	N/A	3.90%
Equivalent single discount rate for benefit obligations	4.48%	N/A	4.19%	N/A
Equivalent single discount rate for service cost	4.63	N/A	4.59	N/A
Equivalent single discount rate for interest cost	3.88	N/A	3.44	N/A
Expected long-term return on plan assets	6.75	7.25	N/A	N/A
Rate of compensation increase	3.75	3.75	3.75	3.75