Description of the terms and benefits provided by the employer's defined contribution plans. A defined contribution plan provides benefits in return for services rendered, provides an individual account for each participant, and has terms that specify how contributions to the individual's account are to be determined rather than the amount of benefits the individual is to receive. Under a defined contribution pension plan, the benefits a participant will receive depend solely on the amount contributed to the participant's account, the returns earned on investments of those contributions, and forfeitures of other participants' benefits that may be allocated to such participant's account. A description of the plan(s) including employee groups covered, the basis for determining contributions, and the nature and effects of significant matters affecting comparability of information for all periods presented.

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The amount of pension benefit costs recognized during the period for (1) defined benefit plans and (2) defined contribution plans. For defined benefit plans, pension expense includes the following components: service cost, interest cost, expected return on plan assets, gain (loss) on plan assets, prior service cost or credit, transition asset or obligation, and gain (loss) due to settlements or curtailments. For defined contribution plans, the pension expense generally equals the firm's contribution to employees' accounts (if the firm contributes) during the period.

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Pension And Profit-Sharing Plans (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Defined Benefit Plan Disclosure [Line Items]
Percentage of employee pay employer matches	4.25%
401(k)/Profit-Sharing Plan
Defined Benefit Plan Disclosure [Line Items]
Matching contributions by employer, description	The Company makes matching contributions on behalf of each eligible participant in an amount equal to 100% of the first 3% and an additional 25% of the next 5%, for a maximum total of 4.25% of the employee’s compensation.
Minimum working hours per employee required to be eligible for discretionary contribution	1000 hours
Expenses related to retirement programs	$ 7.1	$ 5.3	$ 3.9
First 3% Of Employee Pay
Defined Benefit Plan Disclosure [Line Items]
Percentage of employee pay employer matches	3.00%
Percentage of employee contribution employer matches	100.00%
More Than 3% To 5% Of Employee Pay
Defined Benefit Plan Disclosure [Line Items]
Percentage of employee pay employer matches	5.00%
Percentage of employee contribution employer matches	25.00%