Subsequent Events Subsequent Events (Details) - USD ($) $ / shares in Units, $ in Thousands, shares in Millions		9 Months Ended
	Oct. 05, 2017	Sep. 30, 2017	Sep. 30, 2016
Subsequent Event [Line Items]
Net proceeds from issuance of common stock		$ 19,378	$ 0
Subsequent Event
Subsequent Event [Line Items]
Stock issued (in shares)	7.7
Offering price (in dollars per share)	$ 37.50
Net proceeds from issuance of common stock	$ 271,300
Underwriters' Additional Purchase Option [Member] | Subsequent Event
Subsequent Event [Line Items]
Stock issued (in shares)	1.0