Employee and Retiree Benefit Plans (Narrative) (Details) - USD ($)	12 Months Ended			120 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2016
Pension and Other Postretirement Benefits Disclosure [Line Items]
Future annual rate of increase in cost of health care for 2016 to measure postretirement benefit obligations	7.20%
Ultimate rate of health care cost in 2028 and thereafter	4.50%
Equity securities minimum market capitalization	$ 100,000,000			$ 100,000,000
Weighted average expected return on plan asset	5.62%
Basis used to determine expected return on plan asset, average expected investment expenses	0.60%
Perentage return on plan assets				5.69%
Defined benefit plan, percentage of employer's matching contribution	6.00%
Thrift plan expense	$ 7,395,000	$ 7,607,000	$ 10,229,000
Investment 2 [Member]
Pension and Other Postretirement Benefits Disclosure [Line Items]
Domestic plan, investment notice period	90 days
Investment 3 [Member]
Pension and Other Postretirement Benefits Disclosure [Line Items]
Domestic plan, investment lock up period	3 years
Domestic plan, investment notice period	95 days
Foreign Other Postretirement Benefit Plans [Member]
Pension and Other Postretirement Benefits Disclosure [Line Items]
Contributions to benefit plans	$ 28,000
Expected benefit plan contributions to be made during next year	24,000
Domestic postretirement benefits plan [Member]
Pension and Other Postretirement Benefits Disclosure [Line Items]
Contributions to benefit plans	3,554,000
Expected benefit plan contributions to be made during next year	5,243,000
Domestic defined benefit pension plans [Member]
Pension and Other Postretirement Benefits Disclosure [Line Items]
Contributions to benefit plans	7,499,000
Expected benefit plan contributions to be made during next year	18,459,000
Foreign Plans [Member]
Pension and Other Postretirement Benefits Disclosure [Line Items]
Contributions to benefit plans	687,000
Expected benefit plan contributions to be made during next year	$ 7,022,000
United Kingdom [Member]
Pension and Other Postretirement Benefits Disclosure [Line Items]
Target interest and inflation rate hedge ratio	100.00%
Maximum [Member]
Pension and Other Postretirement Benefits Disclosure [Line Items]
Investment Manager's portfolio to be held in equity securities of any one issuer	10.00%			10.00%
Equity Securities [Member]
Pension and Other Postretirement Benefits Disclosure [Line Items]
Target allocations of plan assets, minimum	40.00%
Target allocations of plan assets, maximum	70.00%
Weighted average expected return on plan asset	7.91%
Equity Securities [Member] | United Kingdom [Member]
Pension and Other Postretirement Benefits Disclosure [Line Items]
Target allocations of plan assets	60.00%
Equity Securities [Member] | Canada [Member] | Foreign Other Postretirement Benefit Plans [Member]
Pension and Other Postretirement Benefits Disclosure [Line Items]
Target allocations of plan assets, minimum	40.00%
Target allocations of plan assets, maximum	75.00%
Target allocations of plan assets	60.00%
Fixed Income Securities [Member]
Pension and Other Postretirement Benefits Disclosure [Line Items]
Target allocations of plan assets, minimum	30.00%
Target allocations of plan assets, maximum	60.00%
Fixed income portfolio, maximum average maturity years	11 years
Weighted average expected return on plan asset	4.21%
Fixed Income Securities [Member] | United Kingdom [Member]
Pension and Other Postretirement Benefits Disclosure [Line Items]
Target allocations of plan assets	40.00%
Fixed Income Securities [Member] | Canada [Member] | Foreign Other Postretirement Benefit Plans [Member]
Pension and Other Postretirement Benefits Disclosure [Line Items]
Target allocations of plan assets, minimum	25.00%
Target allocations of plan assets, maximum	45.00%
Target allocations of plan assets	35.00%
US Long/Short Equity Fund [Member]
Pension and Other Postretirement Benefits Disclosure [Line Items]
Target allocations of plan assets, minimum	0.00%
Target allocations of plan assets, maximum	15.00%
Cash and Equivalents [Member]
Pension and Other Postretirement Benefits Disclosure [Line Items]
Target allocations of plan assets, minimum	0.00%
Target allocations of plan assets, maximum	15.00%
Cash [Member] | Canada [Member] | Foreign Other Postretirement Benefit Plans [Member]
Pension and Other Postretirement Benefits Disclosure [Line Items]
Target allocations of plan assets, minimum	0.00%
Target allocations of plan assets, maximum	15.00%
Target allocations of plan assets	5.00%
Emerging Market Commingled Equity Fund [Member]
Pension and Other Postretirement Benefits Disclosure [Line Items]
Domestic plan, investment notice period	10 days