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Present value of lessee's discounted obligation for lease payments from operating lease.

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Recent Accounting Standards (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Jan. 01, 2019	Dec. 31, 2018	Mar. 31, 2018
Accounting Changes and Error Corrections [Abstract]
ROU assets	$ 33,316	$ 31,724
Lease liability	34,159	$ 32,579
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Retained earnings	$ 1,389,438		$ 1,363,772
Accounting Standards Update 2018-02 [Member] \| New Accounting Pronouncement, Early Adoption, Effect [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Retained earnings				$ 19,331