Retirement Plans (Details) - Defined Benefit Plan [Member] - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 661	$ 635	$ 1,323	$ 1,267
Interest cost	473	603	945	1,202
Expected return on plan assets	(324)	(480)	(646)	(954)
Amortization of prior service cost	0	43	0	86
Amortization of actuarial loss (gain)	74	(157)	147	(317)
Curtailment gain	0	(115)	0	(115)
Total defined benefit expense	$ 884	$ 529	$ 1,769	$ 1,169