Stockholders' Equity Note Disclosure [Text Block] (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Aug. 31, 2016
Treasury Stock, Shares, Acquired	2,289,502
Treasury Stock, Value, Acquired, Cost Method	$ 46,527	$ 3,522	$ 1,820
TREASURY STOCK, AT COST
Treasury Stock, Shares, Acquired	2,289,502	214,558	143,307
Treasury Stock, Value, Acquired, Cost Method	$ 46,527	$ 3,522	$ 1,820
Stock Issued During Period, Shares, Share-based Compensation, Gross	72,312
TREASURY STOCK, AT COST | Employee Stock Option
Stock Issued During Period, Shares, Share-based Compensation, Gross	69,012
Private Placement Member
Treasury Stock, Shares, Acquired	703,000
Treasury Stock, Value, Acquired, Cost Method	$ 13,975
Tender Offer
Treasury Stock, Shares, Acquired	1,385,118
Treasury Stock, Value, Acquired, Cost Method	$ 27,702
IhcShareRepurchaseProgramMember
Stock Repurchase Program, Number of Shares Authorized to be Repurchased				3,000,000
Stock Repurchase Program, Remaining Number of Shares Authorized to be Repurchased	1,991,058