Employee Benefit Plans (Defined Benefit Plans Disclosure) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 3,138	$ 2,654
Interest cost	1,386	1,330
Expected return on plan assets	(1,884)	(1,554)
Amortization of prior service cost	60	83
Amortization of prior actuarial loss	911	1,094
Total	3,611	3,607
Other Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	757	636
Interest cost	580	530
Expected return on plan assets	0	0
Amortization of prior service cost	(329)	(329)
Amortization of prior actuarial loss	644	498
Total	$ 1,652	$ 1,335