Earnings Per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Numerator:
Net income available to common shareholders	$ 21,569	$ 12,311
Denominator:
Basic weighted average shares outstanding	16,883,111	15,473,777
Effect of dilutive securities:
SARs and options	330,075	450,686
Convertible notes		776,015
Restricted stock	67,259	17,509
Diluted weighted average shares outstanding	17,280,445	16,717,987
Basic earnings per common share	$ 1.28	$ 0.80
Diluted earnings per common share	$ 1.25	$ 0.74