Employee Benefits (Stock Comp Expense Summary table) (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	$ 10,305	$ 15,283	$ 16,430
Restricted Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total income tax benefit recognized related to stock-based compensation	1,932	3,592	6,168
Restricted Stock \| Service condition restricted stock expense
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Add: Restricted stock expense	7,240	9,941	10,334
Restricted Stock \| Performance-based restricted stock expense
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Add: Restricted stock expense	2,388	4,760	5,387
Restricted Stock \| Restricted stock expense under the Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Add: Restricted stock expense	9,628	14,701	15,721
Restricted Stock \| Canadian Plan restricted stock expense
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Add: Restricted stock expense	$ 677	$ 582	$ 709

Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

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Amount of noncash expense for share-based payment arrangement.

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