Stock-Based Compensation Plans (Summary Of Restricted Stock Activity) (Detail) (USD $)	0 Months Ended	9 Months Ended
	Feb. 20, 2013	Sep. 30, 2013
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward]
Options outstanding, at end of period, Weighted-Average Exercise Price (in dollars per share)		$ 28.25
Time Based Restricted Stock Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward]
Restricted stock, at beginning of period, Number of Shares		249,294
Restricted stock, at beginning of period, Weighted-average Grant Date Fair Value (in dollars per share)		$ 22.12
Granted, Number of Shares		222,585
Granted, Weighted-average Grant Date Fair Value (in dollars per share)		$ 22.80
Vested, Number of Shares		154,133	[1]
Vested, Weighted-average Grant Date Fair Value (in dollars per share)		$ 21.78	[1]
Forfeited/Modified Number of Shares		20,531
Forfeited/Modified Weighted-average Grant Date Fair Value (in dollars per share)		$ 22.40
Restricted stock, at end of period, Number of Shares		297,215
Options outstanding, at end of period, Weighted-Average Exercise Price (in dollars per share)		$ 22.55
Performance Based Restricted Stock Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward]
Restricted stock, at beginning of period, Number of Shares		94,407
Restricted stock, at beginning of period, Weighted-average Grant Date Fair Value (in dollars per share)		$ 25.44
Granted, Number of Shares	163,519	163,519
Granted, Weighted-average Grant Date Fair Value (in dollars per share)		$ 24.04
Vested, Number of Shares		64,169	[1]
Vested, Weighted-average Grant Date Fair Value (in dollars per share)		$ 24.77	[1]
Forfeited/Modified Number of Shares		34,825
Forfeited/Modified Weighted-average Grant Date Fair Value (in dollars per share)		$ 24.55
Restricted stock, at end of period, Number of Shares		158,932
Options outstanding, at end of period, Weighted-Average Exercise Price (in dollars per share)		$ 24.46
Time Based Restricted Stock Unit Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward]
Restricted stock, at beginning of period, Number of Shares		33,742
Restricted stock, at beginning of period, Weighted-average Grant Date Fair Value (in dollars per share)		$ 22.12
Granted, Number of Shares		0
Granted, Weighted-average Grant Date Fair Value (in dollars per share)		$ 0.00
Vested, Number of Shares		19,700	[1]
Vested, Weighted-average Grant Date Fair Value (in dollars per share)		$ 22.21	[1]
Forfeited/Modified Number of Shares		9,778
Forfeited/Modified Weighted-average Grant Date Fair Value (in dollars per share)		$ 21.67
Restricted stock, at end of period, Number of Shares		4,264
Options outstanding, at end of period, Weighted-Average Exercise Price (in dollars per share)		$ 22.75

[1] Vested for purposes of recording compensation expense on a straight-line basis.