Significant Accounting Policies Earnings per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Significant Accounting Policies [Abstract]
Net Income Loss	$ 72,967	$ 72,677	$ 75,173
Weighted Average Number of Shares Outstanding, Basic	81,980	82,378	83,298
Basic EPS	$ 0.89	$ 0.88	$ 0.90
Dilutive Securities, Effect on Basic Earnings Per Share, Including Options and Restrictive Stock Units	$ 0	$ 0	$ 0
Incremental Common Shares Attributable to Share-based Payment Arrangements	44	32	38
Net Income (Loss) Available to Common Stockholders, Diluted	$ 72,967	$ 72,677	$ 75,173
Weighted Average Number of Shares Outstanding, Diluted	82,024	82,410	83,336
Diluted EPS	$ 0.89	$ 0.88	$ 0.90