Basis of Presentation and Organization Recent Accounting Pronouncements (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating Cash Flow Increase [Member]
Item Effected [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification	$ 6,227,000	$ 5,538,000
Income Tax Benefit [Member]
Item Effected [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification	$ 6,082,000	$ 5,499,000	$ 7,925,000
Weighted Average Diluted Shares Outstanding Impact [Member]
Item Effected [Line Items]
Adoption of Recent Accounting Pronouncement Impact on Weighted Average Shares Outstanding	159,387	240,016