Stock-Based Compensation Plans (Summary Of Plans' Restricted Share And Performance-Vested Stock Award Activity) (Detail) - $ / shares	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014	Dec. 31, 2013
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Shares, Beginning of the Period	146,112	181,522
Shares, Granted	14,907	11,430
Shares, Vested and issued	(14,015)	(32,328)
Shares, Forfeited	0	(5,387)
Shares, Outstanding, End of the Period	147,004	155,237
Shares, Vested, but not issuable	85,000	85,000
Weighted Average Grant-Date Fair Value	$ 48.07	$ 45.65	$ 47.45	$ 43.39
Weighted Average Grant-Date Fair Value, Granted	45.35	46.10
Weighted Average Grant-Date Fair Value, Vested and issued	38.78	34.57
Weighted Average Grant-Date Fair Value, Forfeited	0.00	36.89
Weighted Average Grant-Date Fair Value, Vested, but not issuable	$ 51.88	$ 51.88
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Shares, Beginning of the Period	295,679	307,512
Shares, Granted	104,191	93,123
Shares, Vested and issued	(78,590)	(15,944)
Shares, Forfeited	(33,522)	(87,046)
Shares, Outstanding, End of the Period	287,758	297,645
Weighted Average Grant-Date Fair Value	$ 42.93	$ 38.18	$ 38.18	$ 34.01
Weighted Average Grant-Date Fair Value, Granted	44.17	46.85
Weighted Average Grant-Date Fair Value, Vested and issued	31.10	33.28
Weighted Average Grant-Date Fair Value, Forfeited	$ 32.62	$ 33.64