Nature of Business and Significant Accounting Policies (Details 2) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Cash paid for:
Interest	$ 10,239	$ 1,119	$ 1,631
Taxes	74,333	106,215	111,778
Non-cash transactions:
Conversion of convertible notes to common stock	0	0	58,752
Stock issued for business acquisition	$ 0	$ 0	$ 2,121