Stock-Based Compensation (Summary Of Stock-Based Awards) (Details) shares in Thousands	9 Months Ended
	Sep. 30, 2017 $ / shares shares
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Non-vested shares outstanding, shares or units, beginning balance | shares	525
Granted, shares or units | shares	302
Vested, shares or units | shares	(185)
Forfeited, shares or units | shares	(34)
Non-vested shares outstanding, shares or units, ending balance | shares	608
Non-vested outstanding, weighted-average grant date fair value, beginning balance | $ / shares	$ 22.57
Granted, weighted-average grant date fair value | $ / shares	31.64
Vested, weighted-average grant date fair value | $ / shares	21.43
Forfeited, weighted-average grant date fair value | $ / shares	23.96
Non-vested outstanding, weighted-average grant date fair value, ending balance | $ / shares	$ 27.34
Performance-Based Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Non-vested shares outstanding, shares or units, beginning balance | shares	227
Granted, shares or units | shares	172
Forfeited, shares or units | shares	(51)
Non-vested shares outstanding, shares or units, ending balance | shares	348
Non-vested outstanding, weighted-average grant date fair value, beginning balance | $ / shares	$ 21.43
Granted, weighted-average grant date fair value | $ / shares	31.6
Forfeited, weighted-average grant date fair value | $ / shares	18.69
Non-vested outstanding, weighted-average grant date fair value, ending balance | $ / shares	$ 26.84