Note 7 - Employee Benefit Plans (Tables)

6 Months Ended

Jun. 30, 2018

Notes Tables

Schedule of Net Benefit Costs [Table Text Block]

	Three Months Ended June 30,
	2018			2017
Service cost	$	1,252		$	1,196
Interest cost		1,377			1,339
Expected return on plan assets		(1,634	)		(1,462	)
Amortization of prior service cost		15			(84	)
Amortization of net loss		931			1,033
Net periodic pension cost	$	1,941		$	2,022

	Six Months Ended June 30,
	2018			2017
Service cost	$	2,504		$	2,392
Interest cost		2,754			2,678
Expected return on plan assets		(3,268	)		(2,924	)
Amortization of prior service cost		30			(168	)
Amortization of net (gain) loss		1,862			2,066
Net periodic pension cost	$	3,882		$	4,044