Earnings Per Common Share - Computation of Basic and Diluted EPS (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Earnings Per Share [Abstract]
Net income	$ 193,865	$ 169,876	$ 165,423	$ 196,819	$ 156,216	$ 182,358	$ 115,123	$ 148,125	$ 725,983	$ 601,822	$ 563,648
Basic weighted average common shares outstanding	82,473	82,470	82,454	82,640	82,737	83,602	83,666	84,870	82,508	83,716	84,644
Effect of dilutive securities:
Stock options, RSUs and PSUs									971	801	892
Diluted weighted average common shares outstanding	83,578	83,554	83,295	83,493	83,707	84,479	84,349	85,548	83,479	84,517	85,536
Earnings per basic common share	$ 2.35	$ 2.06	$ 2.01	$ 2.38	$ 1.89	$ 2.18	$ 1.38	$ 1.75	$ 8.80	$ 7.19	$ 6.66
Earnings per diluted common share	$ 2.32	$ 2.03	$ 1.99	$ 2.36	$ 1.87	$ 2.16	$ 1.36	$ 1.73	$ 8.70	$ 7.12	$ 6.59