Compensation Plans 401(k) Plan (Details) (401 (k) Plan[Member], USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
401 (k) Plan[Member]
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Maximum employee deferral percentage	60.00%
Employer match, maximum percentage	6.00%
Employer contribution	$ 4.2	$ 3.5	$ 2.9

Maximum percentage of employee gross pay, by the terms of the plan, that the employer may contribute to a defined contribution plan.

No definition available.

Name:	us-gaap_DefinedContributionPlanMaximumAnnualContributionPerEmployeePercent
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration