Stock-Based Compensation Plans (Details Textual) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Stock-based Compensation Plans (Textual) [Abstract]
Unrecognized compensation cost related to stock based compensation arrangements	$ 36,600
Weighted average period for recognition of cost	3 years 5 months 29 days
Additional Stock-based Compensation Plans (Textual) [Abstract]
Stock-based compensation cost	13,899	11,931	10,919
Income tax benefit for stock based compensation arrangements	3,700	3,200	2,900
Cash received from option exercises and employee stock purchase plan purchases	5,600	5,700	4,200
Tax benefit realized for the tax deductions	3,000	3,000	2,600
Increase in financing activities and decrease in operating activities due to tax benefit relating to excess stock based compensation deductions	2,993	2,875	2,478
Employee Stock Purchase Plan [Member]
Stock-based Compensation Plans (Textual) [Abstract]
Expiry date for stock options grant	Mar. 06, 2016
Shares authorized under Employee stock option plan	3,500,000
Employee stock purchase price in percentage of fair market value	85.00%
Shares remaining in reserve for future issuance	619,964
Shares issued to employee under purchase plan	104,295	106,782	109,601
Weighted average fair value of employee stock purchase rights issued	$ 14.37	$ 11.90	$ 9.74
Long Term Incentive Plan [Member]
Stock-based Compensation Plans (Textual) [Abstract]
Maximum number of shares available for issuance under the plan	7,500,000
Expiry date for stock options grant	Mar. 08, 2017
Shares available for granted under the incentive plan	773,174
Restricted Stock [Member]
Stock-based Compensation Plans (Textual) [Abstract]
Fair value of shares vested	$ 9,800	$ 8,900	$ 9,000
Restricted Stock [Member] \| Maximum [Member]
Stock-based Compensation Plans (Textual) [Abstract]
Range of forfeiture provisions	5 years
Restricted Stock [Member] \| Minimum [Member]
Stock-based Compensation Plans (Textual) [Abstract]
Range of forfeiture provisions	6 months

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Employee service share based compensation tax benefit realized from exercise of stock options and vesting of restricted shares.

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Employee common stock purchase price in percentage of fair market value.

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Maximum number of shares available for issuance under the plan.

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- Definition

The total cash inflow associated with the amount received from employees to purchase company stock, including stock option exercises.

+ References

No definition available.

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Range of forfeiture provisions.

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Shares remaining in reserve for future issuance.

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Weighted average fair value of employee stock purchase rights issued.

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No definition available.

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As of the balance sheet date, the aggregate unrecognized cost of equity-based awards made to employees under equity-based compensation awards that have yet to vest.

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-Publisher FASB

-Name Accounting Standards Codification

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Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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The total recognized tax benefit related to compensation cost for equity-based payment arrangements recognized in income during the period.

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Amount of excess tax benefit (tax deficiency) that arises when compensation cost from non-qualified share-based compensation recognized on the entity's tax return exceeds (is less than) compensation cost from equity-based compensation recognized in financial statements. Excess tax benefit (tax deficiency) increases (decreases) net cash provided by financing activities.

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The aggregate amount of noncash, equity-based employee remuneration. This may include the value of stock or unit options, amortization of restricted stock or units, and adjustment for officers' compensation. As noncash, this element is an add back when calculating net cash generated by operating activities using the indirect method.

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The total fair value of equity-based awards for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement.

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Date the equity-based award expires, in CCYY-MM-DD format.

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The maximum number of shares (or other type of equity) originally approved (usually by shareholders and board of directors), net of any subsequent amendments and adjustments, for awards under the equity-based compensation plan. As stock or unit options and equity instruments other than options are awarded to participants, the shares or units remain authorized and become reserved for issuance under outstanding awards (not necessarily vested).

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The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

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Number of shares issued during the period as a result of an employee stock purchase plan.

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