Earnings Per Share (Computation Of Basic And Diluted Earnings Per Share) (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Earnings Per Share [Abstract]
Net income attributable to common shareholders	$ 28,079	$ 57,131	$ 136,460	$ 169,796
Average basic shares outstanding	58,971	58,093	58,770	57,814
Effect of dilutive stock options	932	942	964	923
Average diluted shares outstanding	59,903	59,035	59,734	58,737
Earnings per share - basic:
Net income attributable to common shareholders	$ 0.48	$ 0.98	$ 2.32	$ 2.94
Earnings per share - diluted:
Net income attributable to common shareholders	$ 0.47	$ 0.97	$ 2.28	$ 2.89