Capital Stock (Details) - USD ($)		3 Months Ended	12 Months Ended
	May 12, 2017	Dec. 31, 2017	Dec. 31, 2017	Oct. 31, 2017
Capital Stock [Abstract]
Maximum amount receivable from sale of securities under shelf registration	$ 300,000,000
Maximum limit of shares sold by stockholders	3,000,000
Authorized number of shares for issuance in offering program				2,000,000
Issuance of common stock		888,453
Proceeds from issuance of stock, gross		$ 30,000,000
Payments of sales commissions		600,000
Payments of other offering related expenses		300,000
Proceeds from issuance of stock		$ 29,100,000	$ 28,028,000
Remaining number of shares for issuance in offering program		1,100,000	1,100,000