Earnings Per Share (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Earnings per Share anti diluted
Net income	$ 107,774	$ 78,121
Average common shares outstanding-basic (in shares)	3,767,443	3,735,136
Dilutive effect of equity instruments (in shares)	2,770,285	2,746,248
Average common shares outstanding-diluted (in shares)	6,537,728	6,481,384
Net income per common share
Basic (in dollars per share)	$ 0.03	$ 0.02
Diluted (in dollars per share)	$ 0.02	$ 0.01