Income Taxes (Components of Income Taxes) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
The components of income tax expense are as follows:
Current income tax expense									$ 18,239	$ 30,851	$ 14,560
Deferred income tax expense									201	129	12,385
Income tax expense	$ (237)	$ 6,220	$ 4,947	$ 7,510	$ 11,952	$ 5,672	$ 11,073	$ 2,283	$ 18,440	$ 30,980	$ 26,945