Stockholders' Equity Share Repurchases (Details) - USD ($) $ / shares in Units, $ in Thousands		1 Months Ended					4 Months Ended	5 Months Ended	12 Months Ended			15 Months Ended
	Dec. 31, 2020	Jan. 31, 2021	Nov. 30, 2020	Oct. 31, 2020	Mar. 31, 2020	Nov. 30, 2019	Jan. 31, 2021	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Jan. 31, 2021	Nov. 12, 2019
Equity, Class of Treasury Stock [Line Items]
Shares repurchased									5,350,976	5,076,530	2,272,213
Shares repurchased									$ 896,400	$ 710,000	$ 243,500
Forward contract for accelerated share repurchases									$ 75,000	$ 82,500
Common Stock [Member] | 2020 Share Repurchase Program [Member]
Equity, Class of Treasury Stock [Line Items]
Maximum amount of share repurchase program			$ 3,000,000
Expiration date of share repurchase program			Dec. 31, 2023
Shares repurchased									143,343
Shares repurchased									$ 27,000
Common Stock [Member] | 2019 Share Repurchase Program [Member]
Equity, Class of Treasury Stock [Line Items]
Maximum amount of share repurchase program													$ 2,000,000
Remaining authorized repurchase amount that was eliminated													$ 588,300
Shares repurchased									5,207,633
Shares repurchased									$ 869,200
Common Stock [Member] | 2019 Share Repurchase Program [Member] | Subsequent Event [Member]
Equity, Class of Treasury Stock [Line Items]
Shares repurchased												8,463,795
Shares repurchased												$ 1,411,700
Average price of shares repurchased												$ 166.80
Common Stock [Member] | 2019 Share Repurchase Program [Member] | Accelerated Share Repurchase Agreements [Member]
Equity, Class of Treasury Stock [Line Items]
Amount paid under ASR agreements				$ 500,000		$ 550,000
Shares repurchased								3,468,696
Weighted-average price of all shares repurchased under ASR agreement(s)								$ 154.66
Common Stock [Member] | 2019 Share Repurchase Program [Member] | Accelerated Share Repurchase Agreements [Member] | Subsequent Event [Member]
Equity, Class of Treasury Stock [Line Items]
Shares repurchased							2,607,570
Weighted-average price of all shares repurchased under ASR agreement(s)							$ 191.75
Common Stock [Member] | 2019 Share Repurchase Program [Member] | Accelerated Share Repurchase Agreements [Member] | Additional Paid-in Capital [Member]
Equity, Class of Treasury Stock [Line Items]
Forward contract for accelerated share repurchases	$ 75,000
Common Stock [Member] | 2019 Share Repurchase Program [Member] | Accelerated Share Repurchase Agreements [Member] | Initial Shares Delivered [Member]
Equity, Class of Treasury Stock [Line Items]
Shares repurchased				2,374,168		3,022,760
Shares repurchased				$ 425,000		$ 467,500
Common Stock [Member] | 2019 Share Repurchase Program [Member] | Accelerated Share Repurchase Agreements [Member] | Additional Shares Delivered [Member]
Equity, Class of Treasury Stock [Line Items]
Shares repurchased					445,936
Shares repurchased					$ 82,500
Common Stock [Member] | 2019 Share Repurchase Program [Member] | Accelerated Share Repurchase Agreements [Member] | Additional Shares Delivered [Member] | Subsequent Event [Member]
Equity, Class of Treasury Stock [Line Items]
Shares repurchased		233,402
Shares repurchased		$ 75,000
Common Stock [Member] | 2019 Share Repurchase Program [Member] | Accelerated Share Repurchase Agreements [Member] | ASR Agreement 1 [Member]
Equity, Class of Treasury Stock [Line Items]
Amount paid under ASR agreements						$ 275,000
Shares repurchased								1,735,624
Weighted-average price of all shares repurchased under ASR agreement(s)								$ 158.44
Common Stock [Member] | 2019 Share Repurchase Program [Member] | Accelerated Share Repurchase Agreements [Member] | ASR Agreement 1 [Member] | Initial Shares Delivered [Member]
Equity, Class of Treasury Stock [Line Items]
Shares repurchased						1,511,380
Shares repurchased						$ 233,750
Common Stock [Member] | 2019 Share Repurchase Program [Member] | Accelerated Share Repurchase Agreements [Member] | ASR Agreement 1 [Member] | Additional Shares Delivered [Member]
Equity, Class of Treasury Stock [Line Items]
Shares repurchased					224,244
Shares repurchased					$ 41,250
Common Stock [Member] | 2019 Share Repurchase Program [Member] | Accelerated Share Repurchase Agreements [Member] | ASR Agreement 2 [Member]
Equity, Class of Treasury Stock [Line Items]
Amount paid under ASR agreements						$ 275,000
Shares repurchased								1,733,072
Weighted-average price of all shares repurchased under ASR agreement(s)								$ 158.68
Common Stock [Member] | 2019 Share Repurchase Program [Member] | Accelerated Share Repurchase Agreements [Member] | ASR Agreement 2 [Member] | Initial Shares Delivered [Member]
Equity, Class of Treasury Stock [Line Items]
Shares repurchased						1,511,380
Shares repurchased						$ 233,750
Common Stock [Member] | 2019 Share Repurchase Program [Member] | Accelerated Share Repurchase Agreements [Member] | ASR Agreement 2 [Member] | Additional Shares Delivered [Member]
Equity, Class of Treasury Stock [Line Items]
Shares repurchased					221,692
Shares repurchased					$ 41,250
Common Stock [Member] | 2019 Share Repurchase Program [Member] | Accelerated Share Repurchase Agreements [Member] | ASR Agreement 3 [Member]
Equity, Class of Treasury Stock [Line Items]
Amount paid under ASR agreements				$ 250,000
Common Stock [Member] | 2019 Share Repurchase Program [Member] | Accelerated Share Repurchase Agreements [Member] | ASR Agreement 3 [Member] | Subsequent Event [Member]
Equity, Class of Treasury Stock [Line Items]
Shares repurchased							1,303,398
Weighted-average price of all shares repurchased under ASR agreement(s)							$ 191.81
Common Stock [Member] | 2019 Share Repurchase Program [Member] | Accelerated Share Repurchase Agreements [Member] | ASR Agreement 3 [Member] | Initial Shares Delivered [Member]
Equity, Class of Treasury Stock [Line Items]
Shares repurchased				1,187,084
Shares repurchased				$ 212,500
Common Stock [Member] | 2019 Share Repurchase Program [Member] | Accelerated Share Repurchase Agreements [Member] | ASR Agreement 3 [Member] | Additional Shares Delivered [Member] | Subsequent Event [Member]
Equity, Class of Treasury Stock [Line Items]
Shares repurchased		116,314
Shares repurchased		$ 37,500
Common Stock [Member] | 2019 Share Repurchase Program [Member] | Accelerated Share Repurchase Agreements [Member] | ASR Agreement 4 [Member]
Equity, Class of Treasury Stock [Line Items]
Amount paid under ASR agreements				$ 250,000
Common Stock [Member] | 2019 Share Repurchase Program [Member] | Accelerated Share Repurchase Agreements [Member] | ASR Agreement 4 [Member] | Subsequent Event [Member]
Equity, Class of Treasury Stock [Line Items]
Shares repurchased							1,304,172
Weighted-average price of all shares repurchased under ASR agreement(s)							$ 191.69
Common Stock [Member] | 2019 Share Repurchase Program [Member] | Accelerated Share Repurchase Agreements [Member] | ASR Agreement 4 [Member] | Initial Shares Delivered [Member]
Equity, Class of Treasury Stock [Line Items]
Shares repurchased				1,187,084
Shares repurchased				$ 212,500
Common Stock [Member] | 2019 Share Repurchase Program [Member] | Accelerated Share Repurchase Agreements [Member] | ASR Agreement 4 [Member] | Additional Shares Delivered [Member] | Subsequent Event [Member]
Equity, Class of Treasury Stock [Line Items]
Shares repurchased		117,088
Shares repurchased		$ 37,500
$25 Par Preferred Stock [Member]
Equity, Class of Treasury Stock [Line Items]
Shares repurchased									7,426
Shares repurchased									$ 200
Average price of shares repurchased									$ 29.58
Preferred stock, par value	$ 25								$ 25	$ 25	$ 25