Stock-Based Compensation (Summary Of Stock-Based Awards) (Details) shares in Thousands	3 Months Ended
	Mar. 31, 2018 $ / 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	593
Granted, shares or units | shares	333
Vested, shares or units | shares	(198)
Forfeited, shares or units | shares	(56)
Non-vested shares outstanding, shares or units, ending balance | shares	672
Non-vested outstanding, weighted-average grant date fair value, beginning balance | $ / shares	$ 27.47
Granted, weighted-average grant date fair value | $ / shares	30.01
Vested, weighted-average grant date fair value | $ / shares	26.21
Forfeited, weighted-average grant date fair value | $ / shares	26.6
Non-vested outstanding, weighted-average grant date fair value, ending balance | $ / shares	$ 29.18
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	346
Granted, shares or units | shares	109
Forfeited, shares or units | shares	(145)
Non-vested shares outstanding, shares or units, ending balance | shares	310
Non-vested outstanding, weighted-average grant date fair value, beginning balance | $ / shares	$ 26.88
Granted, weighted-average grant date fair value | $ / shares	29.92
Forfeited, weighted-average grant date fair value | $ / shares	23.97
Non-vested outstanding, weighted-average grant date fair value, ending balance | $ / shares	$ 29.31