Schedule II (BALANCE SHEETS - Parent Company Only) (Details) - USD ($) $ in Millions	Dec. 31, 2020		Dec. 31, 2019		Dec. 31, 2018	Dec. 31, 2017
Assets
Investments in subsidiaries and affiliates on equity basis	$ 0		$ 0
Cash	1,747	[1]	1,537	[2]	$ 1,247
Due from subsidiaries and affiliates, net	0		0
Other assets	8,822		7,581
Total assets	190,774		176,943
Liabilities
Accounts payable, accrued expenses, and other liabilities	14,052		12,214
Total liabilities	131,333		121,612
Stockholders' Equity Attributable to Parent [Abstract]
Common Shares	11,064		11,121
Common Shares in treasury (26,872,639 and 27,812,297 shares)	(3,644)		(3,754)
Retained earnings	39,337		36,142
Accumulated other comprehensive income	2,869		619
Total shareholders' equity	59,441		55,331		50,312
Total liabilities and shareholders’ equity	190,774		176,943
Parent Company Only
Assets
Investments in subsidiaries and affiliates on equity basis	56,148		50,853
Total investments	56,148		50,853
Cash	84	[1]	2	[2]	$ 1	$ 3
Due from subsidiaries and affiliates, net	3,522		4,776
Other assets	10		12
Total assets	59,764		55,643
Liabilities
Accounts payable, accrued expenses, and other liabilities	323		312
Total liabilities	323		312
Stockholders' Equity Attributable to Parent [Abstract]
Common Shares	11,064		11,121
Common Shares in treasury (26,872,639 and 27,812,297 shares)	(3,644)		(3,754)
Additional paid-in capital	9,815		11,203
Retained earnings	39,337		36,142
Accumulated other comprehensive income	2,869		619
Total shareholders' equity	59,441		55,331
Total liabilities and shareholders’ equity	$ 59,764		$ 55,643

[1] Chubb maintains two notional multicurrency cash pools (Pools) with a third-party bank. Refer to Note 1 f) for additional information. At December 31, 2020, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.

[2] Chubb maintains two notional multicurrency cash pools (Pools) with a third-party bank. Refer to Note 1 f) for additional information.