Employee Benefit Plans (Defined Benefit Plans Disclosure) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 2,819	$ 2,652	$ 5,399	$ 4,958
Interest cost	1,431	1,076	2,629	2,335
Expected return on plan assets	(1,823)	(1,345)	(3,108)	(2,569)
Amortization of prior service cost	95	75	169	153
Amortization of prior actuarial loss	1,082	1,224	2,163	2,081
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement	256	0	513	0
Total	3,860	3,682	7,765	6,958
Other Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	721	1,015	1,442	2,031
Interest cost	565	643	1,130	1,286
Expected return on plan assets	0	0	0	0
Amortization of prior service cost	(155)	0	(311)	0
Amortization of prior actuarial loss	457	617	914	1,233
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement	0	0	0	0
Total	$ 1,588	$ 2,275	$ 3,175	$ 4,550