Stock-Based Compensation (Narrative) (Details) (USD $) | 0 Months Ended | 3 Months Ended |
Feb. 20, 2014 | Mar. 31, 2014 | Mar. 31, 2013 |
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items] | ' | ' | ' |
Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period (in shares) | ' | 253,662 | ' |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value | ' | $57.38 | ' |
Stock-based compensation | ' | $6,913,000 | $6,739,000 |
Share-based Compensation Arrangement by Share-based Payment Award Accelerated Compensation Cost | ' | 2,500,000 | 3,200,000 |
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized | ' | $20,500,000 | ' |
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition | ' | '26 months 15 days | ' |
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate | 0.69% | ' | ' |
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate | 24.80% | ' | ' |
Restricted Stock [Member] | ' | ' | ' |
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items] | ' | ' | ' |
Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period (in shares) | 45,168 | ' | ' |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value | 55.35 | ' | ' |
Restricted Stock Units (RSUs) [Member] | ' | ' | ' |
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items] | ' | ' | ' |
Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period (in shares) | 161,024 | ' | ' |
Performance Shares [Member] | ' | ' | ' |
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items] | ' | ' | ' |
Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period (in shares) | 47,470 | ' | ' |
Earnings Per Share [Member] | Performance Shares [Member] | ' | ' | ' |
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items] | ' | ' | ' |
Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period (in shares) | 23,735 | ' | ' |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value | 55.35 | ' | ' |
Total Shareholder Return [Member] | Performance Shares [Member] | ' | ' | ' |
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items] | ' | ' | ' |
Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period (in shares) | 23,735 | ' | ' |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value | 77 | ' | ' |