Defined Benefit Pension Plans

3 Months Ended

Mar. 31, 2016

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

The Corporation maintains a tax-qualified defined benefit pension plan for the benefit of certain eligible employees who were hired prior to October 1, 2007. The Corporation also has non-qualified retirement plans to provide supplemental retirement benefits to certain employees, as defined in the plans. The defined benefit pension plans were previously amended to freeze benefit accruals after a 10-year transition period ending in December 2023.

The defined benefit pension plan is funded on a current basis, in compliance with the requirements of ERISA.

Pension benefit costs and benefit obligations incorporate various actuarial and other assumptions, including discount rates, mortality, rates of return on plan assets and compensation increases. Washington Trust evaluates these assumptions annually. In 2015 and prior to 2015, a single weighted-average discount rate was used to calculate interest and service cost components of net periodic benefit cost. For 2016, Washington Trust utilizes a "spot rate approach" in the calculation of interest and service cost. The spot rate approach applies separate discount rates for each projected benefit payment in the calculation of interest and service cost. This approach provides a more precise measurement of interest and service cost by improving the correlation between projected benefit cash flows and their corresponding spot rates. This change was made in conjunction with the annual evaluation of assumptions and did not affect the measurement of the Corporation’s defined benefit obligations at December 31, 2015. It is considered a change in accounting estimate and, accordingly, was accounted for prospectively starting in 2016.

The composition of net periodic benefit cost was as follows:



(Dollars in thousands)	Qualified Pension Plan						Non-Qualified Retirement Plans
Three months ended March 31,	2016			2015			2016		2015
Net Periodic Benefit Cost:
Service cost		$537			$615			$30		$20
Interest cost	644			732			108		122
Expected return on plan assets	(1,158		)	(1,129		)	—		—
Amortization of prior service (credit) cost	(6		)	(6		)	—		—
Recognized net actuarial loss	207			312			62		61
Net periodic benefit cost		$224			$524			$200		$203

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
Three months ended March 31,	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