Net Income Or Loss Per Share (Computation Of Basic And Diluted Earnings Per Share) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Numerator (both basic and diluted):
Net income (loss) available to common stockholders	$ (55,184)	$ (105,642)	$ (48,295)	$ (32,624)	$ (18,808)	$ 9,931	$ 2,443	$ (1,907)	$ (241,745)	$ (8,341)	$ (35,929)
Denominator:
Denominator for basic earnings per share	40,148,000	40,168,000	40,168,000	40,072,000	41,332,000	41,477,000	41,342,000	40,605,000	40,505,429	41,165,940	40,288,218
Denominator for diluted earnings per share	40,148,000	40,168,000	40,168,000	40,072,000	41,332,000	42,213,000	42,043,000	40,605,000	40,505,429	41,165,940	40,288,218
Basic earnings (loss) per common share	$ (1.37)	$ (2.63)	$ (1.20)	$ (0.81)	$ (0.46)	$ 0.24	$ 0.06	$ (0.05)	$ (5.97)	$ (0.20)	$ (0.89)
Diluted earnings (loss) per common share	$ (1.37)	$ (2.63)	$ (1.20)	$ (0.81)	$ (0.46)	$ 0.24	$ 0.06	$ (0.05)	$ (5.97)	$ (0.20)	$ (0.89)