Income Taxes (Details 1)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Effective income tax rate reconciliation to the statutory federal income tax rate
Taxes on income at statutory federal tax rate	35.00%	35.00%	35.00%
State income taxes, net of federal benefit	(7.80%)	1.50%	2.10%
Benefit for unrecognized tax benefits	(1.20%)	(0.60%)	(0.10%)
Effective Income Tax Rate Reconciliation, Nondeductible Expense, Share-based Compensation Cost	7.60%	0.00%	1.00%
Nondeductible goodwill	0.00%	31.70%	0.00%
Income Tax Reconciliation, Nondeductible Expense, Other	5.20%	1.10%	0.70%
Goodwill, Purchase Accounting Adjustments		(1.50%)
Business Acquisition Contingent Consideration Charged To Earnings	5.90%
Other	3.90%	0.60%	(0.10%)
Total provision for income taxes	48.60%	67.80%	38.60%