Condensed Consolidated Statements of Changes In Shareholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Common Stock	Retained Earnings	Accumulated Other Comprehensive Income (Loss)
Beginning balance (in shares) at Dec. 31, 2018		220,255,039
Beginning balance at Dec. 31, 2018	$ 4,056,442	$ 3,512,874	$ 602,482	$ (58,914)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income	74,033		74,033
Other comprehensive income, net of tax	29,632			29,632
Stock-based compensation	754	$ 754
Stock repurchased and retired (in shares)		(108,088)
Stock repurchased and retired	(1,918)	$ (1,918)
Issuances of common stock under stock plans (in shares)		310,257
Issuances of common stock under stock plans	21	$ 21
Cash dividends on common stock	$ (46,394)		(46,394)
Cash dividends on common stock (in dollars per share)	$ 0.21
Ending balance (in shares) at Mar. 31, 2019		220,457,208
Ending balance at Mar. 31, 2019	$ 4,112,326	$ 3,511,731	629,877	(29,282)
Beginning balance (in shares) at Dec. 31, 2018		220,255,039
Beginning balance at Dec. 31, 2018	4,056,442	$ 3,512,874	602,482	(58,914)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income	185,843
Other comprehensive income, net of tax	78,027
Ending balance (in shares) at Jun. 30, 2019		220,498,684
Ending balance at Jun. 30, 2019	4,228,507	$ 3,514,391	695,003	19,113
Beginning balance (in shares) at Mar. 31, 2019		220,457,208
Beginning balance at Mar. 31, 2019	4,112,326	$ 3,511,731	629,877	(29,282)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income	111,810		111,810
Other comprehensive income, net of tax	48,395			48,395
Stock-based compensation	2,722	$ 2,722
Stock repurchased and retired (in shares)		(4,113)
Stock repurchased and retired	(62)	$ (62)
Issuances of common stock under stock plans (in shares)		45,589
Issuances of common stock under stock plans	0	$ 0
Cash dividends on common stock	$ (46,684)		(46,684)
Cash dividends on common stock (in dollars per share)	$ 0.21
Ending balance (in shares) at Jun. 30, 2019		220,498,684
Ending balance at Jun. 30, 2019	$ 4,228,507	$ 3,514,391	695,003	19,113
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income	84,502		84,502
Other comprehensive income, net of tax	25,851			25,851
Stock-based compensation	2,350	$ 2,350
Stock repurchased and retired (in shares)		(300,719)
Stock repurchased and retired	(5,248)	$ (5,248)
Issuances of common stock under stock plans (in shares)		14,169
Issuances of common stock under stock plans	0	$ 0
Cash dividends on common stock	$ (46,446)		(46,446)
Cash dividends on common stock (in dollars per share)	$ 0.21
Ending balance (in shares) at Sep. 30, 2019		220,212,134
Ending balance at Sep. 30, 2019	$ 4,289,516	$ 3,511,493	733,059	44,964
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income	83,750		83,750
Other comprehensive income, net of tax	(15,415)			(15,415)
Stock-based compensation	2,547	$ 2,547
Stock repurchased and retired (in shares)		(2,483)
Stock repurchased and retired	(40)	$ (40)
Issuances of common stock under stock plans (in shares)		19,631
Issuances of common stock under stock plans	0	$ 0
Cash dividends on common stock	$ (46,443)		(46,443)
Cash dividends on common stock (in dollars per share)	$ 0.21
Ending balance (in shares) at Dec. 31, 2019	220,229,282	220,229,282
Ending balance at Dec. 31, 2019	$ 4,313,915	$ 3,514,000	770,366	29,549
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income	(1,851,947)		(1,851,947)
Other comprehensive income, net of tax	138,722			138,722
Stock-based compensation	2,253	$ 2,253
Stock repurchased and retired (in shares)		(486,757)
Stock repurchased and retired	(8,573)	$ (8,573)
Issuances of common stock under stock plans (in shares)		432,595
Issuances of common stock under stock plans	0	$ 0
Cash dividends on common stock	$ (46,578)		(46,578)
Cash dividends on common stock (in dollars per share)	$ 0.21
Ending balance (in shares) at Mar. 31, 2020		220,175,120
Ending balance at Mar. 31, 2020	$ 2,507,611	$ 3,507,680	(1,168,340)	168,271
Beginning balance (in shares) at Dec. 31, 2019	220,229,282	220,229,282
Beginning balance at Dec. 31, 2019	$ 4,313,915	$ 3,514,000	770,366	29,549
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income	(1,799,021)
Other comprehensive income, net of tax	$ 114,059
Ending balance (in shares) at Jun. 30, 2020	220,219,107	220,219,107
Ending balance at Jun. 30, 2020	$ 2,538,339	$ 3,510,145	(1,115,414)	143,608
Beginning balance (in shares) at Mar. 31, 2020		220,175,120
Beginning balance at Mar. 31, 2020	2,507,611	$ 3,507,680	(1,168,340)	168,271
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income	52,926		52,926
Other comprehensive income, net of tax	(24,663)			(24,663)
Stock-based compensation	2,503	$ 2,503
Stock repurchased and retired (in shares)		(3,707)
Stock repurchased and retired	(38)	$ (38)
Issuances of common stock under stock plans (in shares)		47,694
Issuances of common stock under stock plans	$ 0	$ 0
Ending balance (in shares) at Jun. 30, 2020	220,219,107	220,219,107
Ending balance at Jun. 30, 2020	$ 2,538,339	$ 3,510,145	$ (1,115,414)	$ 143,608