Defined Benefit Pension Plans (Tables)

6 Months Ended

Jun. 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						Six months						Three months				Six months
Periods ended June 30,	2016			2015			2016			2015			2016		2015		2016		2015
Net Periodic Benefit Cost:
Service cost		$537			$614			$1,074			$1,229			$31		$19		$61		$39
Interest cost	644			732			1,288			1,464			108		123		216		245
Expected return on plan assets	(1,159		)	(1,128		)	(2,317		)	(2,257		)	—		—		—		—
Amortization of prior service (credit) cost	(5		)	(5		)	(11		)	(11		)	—		—		—		—
Recognized net actuarial loss	207			312			414			624			61		61		123		122
Net periodic benefit cost		$224			$525			$448			$1,049			$200		$203		$400		$406

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 June 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