Employee Benefit Plans (Defined Benefit Plans Disclosure) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 3,169	$ 3,570	$ 6,307	$ 6,224
Interest cost	1,931	1,357	3,317	2,687
Expected return on plan assets	(1,692)	(2,213)	(3,576)	(3,767)
Amortization of prior service cost	61	82	121	165
Amortization of prior actuarial loss	1,231	769	2,142	1,863
Total	4,700	3,565	8,311	7,172
Other Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	757	636	1,514	1,272
Interest cost	579	529	1,159	1,059
Expected return on plan assets	0	0	0	0
Amortization of prior service cost	(329)	(329)	(658)	(658)
Amortization of prior actuarial loss	644	498	1,288	996
Total	$ 1,651	$ 1,334	$ 3,303	$ 2,669