Earnings Per Share (Basic and Diluted Weighted Average Shares Outstanding and Earnings per Share) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Net income	$ (12,058)	$ (1,284)	$ 69,579	$ 29,037	$ 24,153	$ (2,247)	$ 35,401	$ 1,503	$ 85,274	$ 58,810	$ 26,611
Net income attributable to participating securities									(943)	(455)	(77)
Net income attributed to common shares									84,331	58,355	26,534
Weighted average shares - basic									38,730	38,885	39,946
Dilutive effect of stock options									506	149	104
Weighted average shares - diluted									39,236	39,034	40,050
Basic earnings per share	$ (0.31)	$ (0.03)	$ 1.77	$ 0.74	$ 0.62	$ (0.06)	$ 0.90	$ 0.04	$ 2.18	$ 1.50	$ 0.66
Diluted earnings per share	$ (0.31)	$ (0.03)	$ 1.75	$ 0.73	$ 0.61	$ (0.06)	$ 0.90	$ 0.04	$ 2.15	$ 1.50	$ 0.66
Parent Company [Member]
Net income									$ 85,274	$ 58,810	$ 26,611