Unrecognized Tax Benefits Reconciliation (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized tax benefit - January 1	$ 44,537	$ 33,042	$ 29,163
Gross increases - tax positions in prior period		8,332	943
Gross decreases - tax positions in prior period	(425)
Gross increases - tax positions in current period	4,310	4,689	3,086
Settlements	(16,260)	(427)
Lapse of statute of limitations	(262)	(1,099)	(150)
Unrecognized tax benefit - December 31	$ 31,900	$ 44,537	$ 33,042