Current Accounting Developments (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2017	Sep. 30, 2017
Accounting Policies [Abstract]
Net excess tax benefits for restricted stock units	$ 151	$ 4,614

Effective Income Tax Rate Reconciliation, Share-based Compensation, Excess Tax Benefit, Amount

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