Stockholders' Equity and Earnings Per Share (Earnings Per Share Calculation) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Basic:
Net income	$ 237,652	$ 204,994
Weighted-average number of shares outstanding (in shares)	142,025	141,646
Basic EPS (in dollars per share)	$ 1.67	$ 1.45
Diluted:
Net income	$ 237,652	$ 204,994
Weighted-average number of shares outstanding (in shares)	142,025	141,646
Diluted potential common shares (in shares)	1,198	1,198
Weighted-average number of shares outstanding (in shares)	143,223	142,844
Diluted EPS (in dollars per share)	$ 1.66	$ 1.44