Earnings Per Share (Schedule Of Earnings Per Share, Basic And Diluted) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Numerator
Net income	$ 91,817	$ 49,764	$ 38,450	$ 26,126	$ 53,358	$ 27,024	$ 15,495	$ 17,117	$ 206,157	$ 112,994	$ 96,455
Less: Undistributed earnings allocated to participating securities											(59)
Net income allocable to common stockholders									$ 206,157	$ 112,994	$ 96,396
Denominator
Weighted average common shares outstanding - basic									33,312,554	30,886,382	30,084,913
Dilutive effect of restricted stock units									297,544	300,570	306,433
Weighted average common shares outstanding - diluted									33,610,098	31,186,952	30,391,346
Earnings per share:
Basic	$ 2.75	$ 1.49	$ 1.15	$ 0.79	$ 1.65	$ 0.88	$ 0.51	$ 0.57	$ 6.19	$ 3.66	$ 3.20
Diluted	$ 2.72	$ 1.48	$ 1.15	$ 0.78	$ 1.63	$ 0.87	$ 0.51	$ 0.56	$ 6.13	$ 3.62	$ 3.17