Share-Based Compensation (Details) (USD $)	9 Months Ended
	Sep. 30, 2011 Year Installment Bank	Sep. 30, 2010 Year	Sep. 30, 2011
Weighted-average assumptions for options issued during the indicated periods
Dividend yield	0.00%	0.00%
Expected volatility	58.80%	63.00%
Risk-free interest rate	1.90%	2.10%
Expected life of options (in years)	3.8	4.3
Weighted-average grant-date fair value	$ 19.17	$ 12.60
Stock option activity in shares and weighted average price
Options outstanding, beginning of period	$ 29.67
Options outstanding, beginning of period, shares	1,361,779
Options granted	$ 42.56
Options granted, shares	307,394
Options canceled	$ 55.19
Options canceled, shares	(67,529)
Options exercised	$ 22.64
Options exercised, shares	(223,963)
Options outstanding, end of period	$ 32.44
Options outstanding, end of period, shares	1,377,681	1,400,000
Options exercisable, end of period			$ 30.96
Options exercisable, end of period, shares	731,300
Restricted stock activity
Restricted shares outstanding, beginning of period	$ 22.87
Restricted shares outstanding, beginning of period, shares	734,286
Restricted shares granted	$ 40.50
Restricted shares granted, shares	490,050
Restricted shares canceled	$ 31.53
Restricted shares canceled, shares	(30,542)
Restricted shares vested	$ 24.68
Restricted shares vested, shares	(337,556)
Restricted shares outstanding, end of period	$ 31.93
Restricted shares outstanding, end of period, shares	856,238