Earnings per Share Table (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Net Income (Loss) Attributable to Parent [Abstract]
Net income	$ 13,984	$ 17,209
Weighted average common and common equivalent shares outstanding used to calculate basic earnings per share	15,339,690	15,217,360
Common equivalent shares - stock options	8,797	8,492
Common equivalent shares - non-vested stock grants	8,267	0
Weighted Average Number Of Shares Outstanding, Diluted Total	15,356,754	15,225,852
Basic earnings per share	$ 0.91	$ 1.13
Diluted earnings per share	$ 0.91	$ 1.13