Note 1. Principal Accounting Policies Earnings per share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Earnings Per Share [Abstract]
Net income	$ 53,667	$ 42,897	$ 66,560	$ 56,902
Weighted average common shares outstanding	57,128,379	56,354,017	57,043,378	56,226,038
Stock options and nonvested stock	566,312	606,721	533,995	634,057
Weighted average common shares outstanding, diluted	57,694,691	56,960,738	57,577,373	56,860,095
Diluted earnings per share	$ 0.93	$ 0.75	$ 1.16	$ 1.00
Anti-dilutive securities excluded from computation of diluted EPS	499,469	1,119,661	719,958	1,119,661