Earnings Per Share (Earnings Per Share) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Sep. 30, 2018	Sep. 30, 2017
Income (numerator) [Abstract]
Basic earnings (loss) per share, Net income (loss) available to common shareholders	$ 61,277	$ 6,141	$ 14,140	$ 7,281	$ 18,864	$ 7,963	$ 81,558	$ 34,108
Diluted earnings (loss) per share, Net income (loss) available to common shareholders	$ 61,277			$ 7,281			$ 81,558	$ 34,108
Shares (denominator) [Abstract]
Basic earnings (loss) per share, Net income (loss) available to common shareholders (in shares)	56,442,222			55,758,433			56,309,390	55,661,538
Effect of dilutive securities, Common stock options (in shares)	661,079			554,405			775,454	382,371
Diluted earnings (loss) per share, Net income (loss) available to common shareholders (in shares)	57,103,301			56,312,838			57,084,844	56,043,909
Per share amount [Abstract]
Basic earnings (loss) per share, Net income (loss) available to common shareholders (in dollars per share)	$ 1.09			$ 0.13			$ 1.45	$ 0.61
Effect of dilutive securities, Common stock options (in dollars per share)	(0.02)						(0.02)
Net income per share - diluted	$ 1.07			$ 0.13			$ 1.43	$ 0.61
Continuing Operations [Member]
Income (numerator) [Abstract]
Basic earnings (loss) per share, Net income (loss) available to common shareholders	$ 61,301			$ 6,770			$ 81,477	$ 30,670
Diluted earnings (loss) per share, Net income (loss) available to common shareholders	$ 61,301			$ 6,770			$ 81,477	$ 30,670
Shares (denominator) [Abstract]
Basic earnings (loss) per share, Net income (loss) available to common shareholders (in shares)	56,442,222			55,758,433			56,309,390	55,661,538
Effect of dilutive securities, Common stock options (in shares)	661,079			554,405			775,454	382,371
Diluted earnings (loss) per share, Net income (loss) available to common shareholders (in shares)	57,103,301			56,312,838			57,084,844	56,043,909
Per share amount [Abstract]
Basic earnings (loss) per share, Net income (loss) available to common shareholders (in dollars per share)	$ 1.09			$ 0.12			$ 1.45	$ 0.55
Effect of dilutive securities, Common stock options (in dollars per share)	(0.02)						(0.02)
Net income per share - diluted	$ 1.07			$ 0.12			$ 1.43	$ 0.55
Discontinued Operations [Member]
Income (numerator) [Abstract]
Basic earnings (loss) per share, Net income (loss) available to common shareholders	$ (24)			$ 511			$ 81	$ 3,438
Diluted earnings (loss) per share, Net income (loss) available to common shareholders	$ (24)			$ 511			$ 81	$ 3,438
Shares (denominator) [Abstract]
Basic earnings (loss) per share, Net income (loss) available to common shareholders (in shares)	56,442,222			55,758,433			56,309,390	55,661,538
Effect of dilutive securities, Common stock options (in shares)	661,079			554,405			775,454	382,371
Diluted earnings (loss) per share, Net income (loss) available to common shareholders (in shares)	57,103,301			56,312,838			57,084,844	56,043,909
Per share amount [Abstract]
Basic earnings (loss) per share, Net income (loss) available to common shareholders (in dollars per share)				$ 0.01				$ 0.06
Net income per share - diluted				$ 0.01				$ 0.06