Benefit Plans Benefit Plans (Detail 10) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Actual return on plan assets:
Defined Benefit Plan, Plan Assets, Foreign Currency Translation Gain (Loss)	$ (11,532)	$ 36,883
Defined Benefit Plan, Plan Assets, Amount	862,951	919,782	$ 820,272
Fair Value, Inputs, Level 3 [Member]
Actual return on plan assets:
Defined Benefit Plan, Plan Assets Level 3 Reconciliation, Increase (Decrease) for Actual Return (Loss) on Plan Assets Still Held	14	21
Defined Benefit Plan Sales, Total	(85)	(5,809)
Defined Benefit Plan, Purchases, Total	82	108
Defined Benefit Plan, Plan Assets, Foreign Currency Translation Gain (Loss)	(64)	300
Defined Benefit Plan, Plan Assets, Amount	1,461	1,514	6,894
Real Asset Mutual Funds, Commodities
Actual return on plan assets:
Defined Benefit Plan, Plan Assets, Amount	40,267	37,302
Real Asset Mutual Funds, Commodities | Fair Value, Inputs, Level 3 [Member]
Actual return on plan assets:
Defined Benefit Plan, Plan Assets Level 3 Reconciliation, Increase (Decrease) for Actual Return (Loss) on Plan Assets Still Held	0	0
Defined Benefit Plan Sales, Total	0	(5,711)
Defined Benefit Plan, Purchases, Total	0	0
Defined Benefit Plan, Plan Assets, Foreign Currency Translation Gain (Loss)	0	117
Defined Benefit Plan, Plan Assets, Amount	0	0	5,594
Fixed Income Mutual Funds, Insurance Contracts
Actual return on plan assets:
Defined Benefit Plan, Plan Assets, Amount	24,313	24,935
Fixed Income Mutual Funds, Insurance Contracts | Fair Value, Inputs, Level 3 [Member]
Actual return on plan assets:
Defined Benefit Plan, Plan Assets Level 3 Reconciliation, Increase (Decrease) for Actual Return (Loss) on Plan Assets Still Held	14	21
Defined Benefit Plan Sales, Total	(85)	(98)
Defined Benefit Plan, Purchases, Total	82	108
Defined Benefit Plan, Plan Assets, Foreign Currency Translation Gain (Loss)	(64)	183
Defined Benefit Plan, Plan Assets, Amount	$ 1,461	$ 1,514	$ 1,300