Earnings Per Share Attributable to Stockholders (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
Earnings Per Share Attributable to Stockholders [Abstract]
Basic earnings per share attributable to stockholders, Net earnings									$ 136,214	$ 90,981	$ 93,644
Diluted earnings per share attributable to stockholders, Net earnings									$ 136,214	$ 90,981	$ 93,644
Basic earnings per share attributable to stockholders, shares									107,075,845	107,268,425	106,768,856
Effect of dilutive securities: Stock options, shares									356,629	386,403	386,317
Effect of dilutive securities: Stock options, per share										$ (0.01)
Diluted earnings per share attributable to stockholders, shares									107,432,474	107,654,828	107,155,173
Basic earnings (loss) per share	$ 0.43	$ 0.19	$ 0.42	$ 0.22	$ 0.29	$ 0.09	$ 0.35	$ 0.12	$ 1.27	$ 0.85	$ 0.88
Diluted earnings (loss) per share	$ 0.43	$ 0.19	$ 0.42	$ 0.22	$ 0.29	$ 0.09	$ 0.34	$ 0.12	$ 1.27	$ 0.85	$ 0.87