Share-Based Compensation Level 4 (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended	9 Months Ended				9 Months Ended		9 Months Ended
	Dec. 31, 2013	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2013 Stock Appreciation Rights (SARs) [Member]	Dec. 31, 2012 Stock Appreciation Rights (SARs) [Member]	Dec. 31, 2013 Restricted Stock	Mar. 31, 2013 Restricted Stock	Dec. 31, 2013 Restricted Stock Units (RSUs)	Dec. 31, 2012 Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Item]
Remaining shares available for grant	3,385,314	3,385,314
Weighted-average assumptions used for options granted:
Risk-free interest rate		0.95%	1.21%
Expected life of options		5 years 8 months 12 days	5 years 9 months 15 days
Exptected dividend yield of stock		2.22%	2.15%
Expected volatility of stock		31.22%	31.24%
Estimated forfeiture rate		1.44%	1.83%
Summary of share option activity:
Number of Options, Outstanding, Beginning of Period		2,657,133
Weighted Average Exercise Price, Outstanding, Beginning of Period		$ 28.40
Number of Options, Granted		322,710
Weighted Average Exercise Price, Granted		$ 45.26
Number of Options, Exercised		(454,301)
Weighted Average Exercise Price, Exercised		$ 25.89
Number of Options, Forfeited		(17,350)
Weighted Average Exercise Price, Forfeited		$ 35.50
Number of Options, Canceled		450
Weighted Average Exercise Price, Canceled		$ 23.62
Number of Options, Outstanding, End of Period	2,507,742	2,507,742
Weighted Average Exercise Price, Outstanding, End of Period	$ 30.98	$ 30.98
Average Remaining Contractual Term, Outstanding	5 years 8 months 12 days
Aggregate Intrinsic Value, Outstanding	$ 42,803	$ 42,803
Number of Options, Exercisable	1,819,558	1,819,558
Weighted Average Exercise Price, Exercisable	$ 28.29	$ 28.29
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term	4 years 7 months 24 days
Aggregate Intrinsic Value, Exercisable	35,948	35,948
Non-vested stock options outstanding expected to vest	679,203	679,203
Common Stock, Fair Market Value Per Share	$ 48.05	$ 48.05
Total intrinsic value of stock options exercised		8,620	5,603
Net cash proceeds from the exercise of stock options		11,877	14,517
Tax benefit from stock option exercises		1,864	2,161
Weighted average grant date fair value of stock option grants, per share		$ 10.59	$ 7.32
Summary of non-vested restricted share activity:
Number of Restricted Shares, Non-vested at Beginning of Period						737,343		0
Number of Restricted Shares, Granted						253,136		32,796
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value						$ 45.19
Number of Restricted Shares, Vested						(61,719)		(17,470)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value						$ 37.33
Number of Restricted Shares, Canceled						(26,203)		0
Number of Restricted Shares, Non-vested at End of Period						902,557		15,326
Weighted-Average Grant Date Fair Value, Non-vested at End of Period						$ 36.22	$ 32.81
Fair Value, Share-based Payment Awards, Other than Options						2,956
FairValueOfOutstandingCashSettledRestrictedShareUnits								1,330	1,208
Unrecognized compensation cost related to nonvested share-based compensation granted	22,814	22,814
Weighted average period for recognition of unrecognized compensation cost		2 years 3 months 29 days
FairValueOfOutstandingStockAppreciationRights				$ 1,473	$ 888
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value						$ 34.64