Shareholders' Equity Shareholders' Equity (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Statement of Stockholders' Equity [Abstract]
Common Stocks, Including Additional Paid in Capital	$ 5,364	$ 91,162
Stock Issued During Period, Value, Share-based Compensation, Net of Forfeitures	3,232
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition	5,926
Stock Repurchased During Period, Value	$ (94,956)
Common Stock, Dividends, Per Share, Cash Paid	$ 0.16
Dividends, Common Stock, Cash	$ 22,200