CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY (DEFICIT) (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2013	Dec. 31, 2012
Treasury stock, shares acquired	381,800	3,491,591
Tax benefit of stock options exercised	$ 16,336	$ 88,185
Shares reissued from treasury stock	1,031,850	6,880,678
Other stock issuances, shares		4,777
Restricted Stock [Member]
Tax benefit of stock options exercised	$ 370	$ 202
Shares reissued from treasury stock	49,467	41,908
Employee stock purchase plan [Member]
Shares reissued from treasury stock	7,032	6,074