Intangible Assets (Details 2) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Summary of reconciliation of goodwill
Balance at the beginning of the year	$ 84,036	$ 72,936
Current year additions	4,717	11,100
Balance at the end of the year	$ 88,753	$ 84,036