Employee Benefit Plans (Other) (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Pension Contributions	$ 4,000
Defined Contribution Plan, Cost Recognized			$ 10,800	$ 10,000	$ 5,700
Common Stock, Shares, Outstanding	84,368,000		84,368,000	88,228,000
Savings Plan 401k [Member]
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Common Stock, Shares, Outstanding	741,019		741,019	820,101
Deferred compensation plan with individual percentage of total shares outstanding	0.90%		0.90%
Deferred Compensation, Share-based Payments [Member]
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Deferred compensation plan with individual percentage of salary deferral			80.00%
Plan assets at fair value at year end	$ 28,000		$ 28,000	$ 27,400
Deferred compensation plan, unfunded liability	34,500		34,500	32,200
Forecast [Member]
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Pension Contributions		$ 9,900
SERP And Restoration Plans [Member]
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Defined Benefit Plan, Plan Amendments			2,347	0
Plan assets at fair value at year end	$ 25,225		$ 25,225	$ 21,175	$ 0