Schedule II (BALANCE SHEETS - Parent Company Only) (Details) - USD ($) $ in Millions	Dec. 31, 2017		Dec. 31, 2016		Dec. 31, 2015		Dec. 31, 2014	[5]
Assets
Short-term investments	$ 3,561		$ 3,002
Other investments (cost – $4,417 and $4,270)	4,672		4,519
Cash	728	[1],[2]	985	[1],[3],[4]	$ 1,775	[1],[5]	$ 655
Other assets	6,358		5,090
Total assets	167,022		159,786
Liabilities
Accounts payable, accrued expenses, and other liabilities	9,545		8,617
Affiliated notional cash pooling program	300		0	[4]
Short-term debt	1,013		500
Total liabilities	115,850		111,511
Stockholders' Equity Attributable to Parent [Abstract]
Common Shares	11,121		11,121
Common Shares in treasury (15,950,685 and 13,815,148 shares)	(1,944)		(1,480)
Retained earnings	27,474		23,613
Accumulated other comprehensive income	543		(314)
Total shareholders' equity	51,172		48,275		29,135
Total liabilities and shareholders’ equity	167,022		159,786
Parent Company Only
Assets
Investments in subsidiaries and affiliates on equity basis	41,909		38,408
Short-term investments	0		2
Other investments (cost – $4,417 and $4,270)	0		25
Total investments	41,909		38,435
Cash	3	[1],[2]	1	[1],[3],[4]	$ 1	[1],[5]	$ 0
Due from subsidiaries and affiliates, net	9,639		10,482
Other assets	3		3
Total assets	51,554		48,921
Liabilities
Accounts payable, accrued expenses, and other liabilities	382		283
Affiliated notional cash pooling program	0		363	[4]
Total liabilities	382		646
Stockholders' Equity Attributable to Parent [Abstract]
Common Shares	11,121		11,121
Common Shares in treasury (15,950,685 and 13,815,148 shares)	(1,944)		(1,480)
Additional paid-in capital	13,978		15,335
Retained earnings	27,474		23,613
Accumulated other comprehensive income	543		(314)
Total shareholders' equity	51,172		48,275
Total liabilities and shareholders’ equity	$ 51,554		$ 48,921

[1] Chubb maintains two notional multi-currency cash pools (Pools) with a third-party bank. Refer to Note 1 f) for additional information. At December 31, 2017 and 2016, 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. At December 31, 2017, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.

[3] Chubb maintains two notional multi-currency cash pools (Pools) with a third-party bank. Refer to Note 1 f) for additional information. At December 31, 2016 and 2015, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.

[4] Chubb maintains two notional multicurrency cash pools (Pools) with a third-party bank. Refer to Note 1 f) for additional information. At December 31, 2016, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.

[5] Chubb maintains two notional multi-currency cash pools (Pools) with a third-party bank. Refer to Note 1 f) for additional information. At December 31, 2015 and 2014, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.