Stockholders' Equity (Narrative) (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Class of Stock [Line Items]
Gross proceeds from issuance of common stock		$ 212,900
Net proceeds from issuance of stock		211,774
Aggregate value of units redeemed		$ 0	$ 0
Preferred stock, par value (in usd per share)	$ 1	$ 1	$ 1
Percentage of restriction on ownership (more than)	3.90%
Common Stock
Class of Stock [Line Items]
Number of shares issued during period		25,000,000
Stock issuance costs		$ 1,100
Net proceeds from issuance of stock		$ 211,800
Number of units redeemed in exchange for common stock (in shares)		1,203,286
Aggregate value of units redeemed		$ 10,100
Preferred Stock
Class of Stock [Line Items]
Number of shares issued in merger			6,900,000