Acquisition (Details) (USD $)	12 Months Ended			3 Months Ended	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010 Avalon [Member]	Dec. 31, 2013 Avalon [Member]	Dec. 31, 2012 Avalon [Member]	Dec. 31, 2011 Avalon [Member]	Dec. 31, 2013 2013 Acquisitions [Member]	May 21, 2013 2013 Acquisitions [Member]
Business Acquisition [Line Items]
Acquisition, net of cash acquired	$ 145,321,000	$ 0	$ 0	$ 8,000,000				$ 145,300,000
Number of Businesses Acquired				1				2
Business Acquisition Contingent Considerations, Potential Payments				7,500,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Long-term Debt									22,000,000
Compensation Expense, acquisition related					$ 1,900,000	$ 1,900,000	$ 1,900,000