Employee Benefit Plans (Net Periodic Benefit Cost) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Other post-employment benefit and pension expense/(benefit)	$ 3,097	$ (53,228)
Qualified Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	1,787	1,593
Interest cost	3,946	3,821
Expected return on plan assets	(4,178)	(3,834)
Amortization of actuarial loss	1,190	1,349
Amortization of prior service cost	(761)	(761)
Plan settlement	441	0
Net periodic benefit cost	2,425	2,168
Less capitalized portion	(134)	(132)
Other post-employment benefit and pension expense/(benefit)	2,291	2,036
Post- employment Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	31	41
Interest cost	959	1,008
Expected return on plan assets	0	0
Amortization of actuarial loss	271	31,704
Amortization of prior service cost	(455)	(88,017)
Plan settlement	0	0
Net periodic benefit cost	806	(55,264)
Less capitalized portion	0	0
Other post-employment benefit and pension expense/(benefit)	$ 806	$ (55,264)