Subsequent Events (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	9 Months Ended
	Aug. 31, 2018	Jul. 31, 2018	Oct. 31, 2017
Subsequent Event [Line Items]
Stock repurchases (in shares)		3,028,118
Stock repurchases		$ 74,787
Average price of shares repurchased (in dollars per share)		$ 24.70
Aggregate shares repurchased (in shares)		3,028,118	0
Subsequent event
Subsequent Event [Line Items]
Stock repurchases (in shares)	472,542
Stock repurchases	$ 12,400
Average price of shares repurchased (in dollars per share)	$ 26.25
Aggregate shares repurchased (in shares)	3,500,660
Authorized funds remaining under stock repurchase program	$ 212,800
3.75% Convertible Senior Notes due October 15, 2018 (New)
Subsequent Event [Line Items]
Conversion price per share equivalent (in dollars per share)		$ 20.17
Convertible notes payable | 3.75% Convertible Senior Notes due October 15, 2018 (New)
Subsequent Event [Line Items]
Maximum cash settlement		$ 400,000
Principal		$ 288,730
Conversion price per share equivalent (in dollars per share)		$ 20.17
Amounts due in excess of aggregate principal amount in cash		$ 111,300