Stock-Based Compensation and Directors Stock Purchase Plan (Summary Of SAR Activity) (Details) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2015 USD ($) $ / shares shares
Stock Appreciation Rights, Shares [Roll Forward]
Outstanding, Shares, Beginning Balance | shares	1,869,224
Granted, Shares | shares	252,149
Forfeited, Shares | shares	(7,837)
Expired, Shares | shares	(1,237)
Exercised, Shares | shares	(523,842)
Outstanding, Shares, Ending Balance | shares	1,588,457
Exercisable, Shares, Ending Balance | shares	1,078,797
Vested and Expected to Vest, Shares | shares	1,563,538
Stock Appreciation Rights, Weighted Average Exercise Price [Roll Forward]
Outstanding, Weighted Average Exercise Price, Beginning Balance | $ / shares	$ 32.34
Granted, Weighted Average Exercise Price | $ / shares	39.43
Forfeited, Weighted Average Exercise Price | $ / shares	37.46
Expired, Weighted Average Exercise Price | $ / shares	35.53
Exercised, Weighted Average Exercise Price | $ / shares	31.44
Outstanding, Weighted Average Exercise Price, Ending Balance | $ / shares	33.74
Exercisable, Weighted Average Exercise Price, Ending Balance | $ / shares	31.56
Vested and Expected to Vest, Weighted Average Exercise Price, Ending Balance | $ / shares	$ 33.67
Outstanding, Weighted Average Remaining Contractual Term (in years)	4 years 4 months
Stock Appreciation Rights Intrinsic Value | $	$ 13,978
Exercisable, Weighted Average Remaining Contractual Term (in years)	2 years 5 months
Exercisable, Aggregate Intrinsic Value, Ending Balance | $	$ 11,845
Vested and Expected to Vest, Weighted Average Remaining Contractual Term (in years)	4 years 2 months
Vested and Expected to Vest, Aggregate Intrinsic Value, Ending Balance | $	$ 13,867