Stock-Based Compensation (Textuals) (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights	retiring executive officers who are at least 57 years of age at the time of retirement, have been employed by the Company for 10 years, and have not been terminated for "cause" as defined under the 2011 Plan.
Shares available for grant/issuance	4,056,600
Granted at target level	$ 47.34	$ 29.56	$ 21.22
Unrecognized compensation expense for all nonvested awards	$ 15,600,000
Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	4 years
Awards, expiration period	10 years
Number of shares reduced for each award granted	1
Stock Appreciation Rights (SARs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	4 years
Awards, expiration period	10 years
Award Types Other than Stock Options and Stock Appreciation Rights [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares reduced for each award granted	2.35
Performance-Vesting Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	133,823	175,498	209,680
Granted at target level	$ 47.21	$ 29.67	$ 21.33
Employee Stock Purchase Plan (ESPP) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for grant/issuance	4,100,000
Percentage of current market price for sales to eligible employees	85.00%
Limitation on payroll deductions of employee's base salary, percent	25.00%
Limitation on payroll deductions of employee's base salary, amount	$ 25,000
Maximum number of shares per employee	2,000
Maximum number of shares per employee, per year	8,000
Purchases of shares	76,751	84,675	103,010
Annual Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	4,200	5,300	2,800
Vesting period	4 years
Granted at target level	$ 48.69	$ 29.56	$ 21.22
Award granted for every bonus shares issued	0.25
Performance-Vesting Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	1,584	25,538	27,100
Deferred Compensation Plans [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of deferred compensation plans	2
Number of deferred stock units	503,873
Number of deferred stock units payable in cash	24,296
Deferred Compensation Plans [Member] | Non-Employee Directors [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	27,144
Granted at target level	$ 43.10