Stock-Based Compensation Plans (Summary Of Plans' Restricted Share And Performance-Vested Stock Award Activity) (Detail) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014	Dec. 31, 2013
Restricted Stock [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	146,112	181,522
Shares, Granted	12,300	2,775
Shares, Vested and issued	(4,925)	(24,900)
Shares, Forfeited	0	(451)
Shares, Outstanding, End of the Period	153,487	158,946
Shares, Vested, but not issuable	85,000	85,000
Weighted Average Grant-Date Fair Value	$ 47.53	$ 44.95	$ 47.45	$ 43.39
Weighted Average Grant-Date Fair Value, Granted	$ 44.11	$ 46.86
Weighted Average Grant-Date Fair Value, Vested and issued	$ 36.74	$ 33.81
Weighted Average Grant-Date Fair Value, Forfeited	$ 0.00	$ 44.29
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	102,828	91,501
Shares, Vested and issued	(78,590)	(15,944)
Shares, Forfeited	(29,926)	(81,551)
Shares, Outstanding, End of the Period	289,991	301,518
Weighted Average Grant-Date Fair Value	$ 42.90	$ 38.12	$ 38.18	$ 34.01
Weighted Average Grant-Date Fair Value, Granted	$ 44.11	$ 46.86
Weighted Average Grant-Date Fair Value, Vested and issued	$ 31.10	$ 33.25
Weighted Average Grant-Date Fair Value, Forfeited	$ 31.41	$ 33.38