Changes in Stockholders' Equity (Narrative) (Details) - USD ($) $ in Millions		1 Months Ended	9 Months Ended
	Nov. 08, 2019	Oct. 31, 2019	Sep. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock repurchase program, outstanding balance authorized to be repurchased			$ 47.1
ASR Program
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Accelerated share repurchases, settlement (payment) or receipt			$ 100.0
Stock repurchased and retired during period (in shares)			1,328,515
ASR Program | Subsequent Event
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Accelerated share repurchases, settlement (payment) or receipt	$ 30.0
Stock repurchased and retired during period (in shares)	308,880	84,570