Recently Adopted and Recently Issued Accounting Standards Details (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Change in Working Capital					$ 27,000
Adoption of new accounting standard (See Note 2)					(397)
Income tax expense	$ 8,270	$ 5,079	$ 25,757	$ 14,913
Stock Compensation Plan
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Income tax expense	$ 100		$ (400)
Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Adoption of new accounting standard (See Note 2)					$ (709)