Fair Value Measurements (Financial Assets and Liabilities Measured at Fair Value On a Recurring Basis) (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2012	Mar. 31, 2012
U.S. government and agency obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Transfers from Level 2 to Level 1	$ 53
Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	5,463	4,879
Available-for-sale securities	4,836	4,659
Derivative assets	199	70
Embedded derivative assets	0	0
Total assets	10,498	9,608
Derivative liabilities	(23)	(43)
Embedded derivative liabilities	(27)	(24)
Total liabilities	(50)	(67)
Total net assets	10,448	9,541
Recurring [Member] | Foreign currency swaps [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	1,975	2,221
Derivative liabilities	(70)	(73)
Recurring [Member] | Interest rate cap [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities	0	0
Recurring [Member] | Interest rate swap [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	660	439
Derivative liabilities	(980)	(1,008)
Recurring [Member] | Debt instruments [Member] | U.S. government and agency obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	135	108
Recurring [Member] | Debt instruments [Member] | Municipal debt securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	19	20
Recurring [Member] | Debt instruments [Member] | Foreign government debt securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	3	3
Recurring [Member] | Debt instruments [Member] | Corporate debt securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	95	107
Recurring [Member] | Debt instruments [Member] | U.S. government agency mortgage-backed securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	100	105
Recurring [Member] | Debt instruments [Member] | Non-agency residential mortgage-backed securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	7	8
Recurring [Member] | Debt instruments [Member] | Non-agency commercial mortgage-backed securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	25	26
Recurring [Member] | Debt instruments [Member] | Asset-backed securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	12	13
Recurring [Member] | Equity instruments [Member] | Municipal debt securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	21
Recurring [Member] | Equity instruments [Member] | Fixed income short-term sector fund [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	40	40
Recurring [Member] | Equity instruments [Member] | Fixed income U.S. government sector fund [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	342	313
Recurring [Member] | Equity instruments [Member] | Fixed income municipal sector fund [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities		21
Recurring [Member] | Equity instruments [Member] | Fixed income investement grade corporate sector fund [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	299	298
Recurring [Member] | Equity instruments [Member] | Fixed income high-yield sector fund [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	37	37
Recurring [Member] | Equity instruments [Member] | Fixed income real return sector fund [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	287	231
Recurring [Member] | Equity instruments [Member] | Fixed income mortgage sector fund [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	637	639
Recurring [Member] | Equity instruments [Member] | Fixed income asset-backed securities sector fund [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	42	41
Recurring [Member] | Equity instruments [Member] | Fixed income emerging market sector fund [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	64	62
Recurring [Member] | Equity instruments [Member] | Fixed income international sector fund [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	164	162
Recurring [Member] | Equity instruments [Member] | Equity mutual fund - S&P 500 index [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	439	451
Recurring [Member] | Money market instruments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	4,074	2,847
Recurring [Member] | Certificates of deposit [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	350	495
Recurring [Member] | Certificates of deposit [Member] | Debt instruments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	1,724
Recurring [Member] | Certificates of deposit [Member] | Debt instruments [Member] | Commercial paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities		1,341
Recurring [Member] | Commercial paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	1,039	1,537
Recurring [Member] | Commercial paper [Member] | Debt instruments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	344
Recurring [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	3,518	2,591
Available-for-sale securities	512	451
Derivative assets	0	0
Embedded derivative assets	0	0
Total assets	4,030	3,042
Derivative liabilities	0	0
Embedded derivative liabilities	0	0
Total liabilities	0	0
Total net assets	4,030	3,042
Recurring [Member] | Level 1 [Member] | Foreign currency swaps [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	0	0
Derivative liabilities	0	0
Recurring [Member] | Level 1 [Member] | Interest rate cap [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities	0	0
Recurring [Member] | Level 1 [Member] | Interest rate swap [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	0	0
Derivative liabilities	0
Recurring [Member] | Level 1 [Member] | Debt instruments [Member] | U.S. government and agency obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	73	0
Recurring [Member] | Level 1 [Member] | Debt instruments [Member] | Municipal debt securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Recurring [Member] | Level 1 [Member] | Debt instruments [Member] | Foreign government debt securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Recurring [Member] | Level 1 [Member] | Debt instruments [Member] | Corporate debt securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Recurring [Member] | Level 1 [Member] | Debt instruments [Member] | U.S. government agency mortgage-backed securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Recurring [Member] | Level 1 [Member] | Debt instruments [Member] | Non-agency residential mortgage-backed securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Recurring [Member] | Level 1 [Member] | Debt instruments [Member] | Non-agency commercial mortgage-backed securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Recurring [Member] | Level 1 [Member] | Debt instruments [Member] | Asset-backed securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Recurring [Member] | Level 1 [Member] | Equity instruments [Member] | Municipal debt securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0
Recurring [Member] | Level 1 [Member] | Equity instruments [Member] | Fixed income short-term sector fund [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Recurring [Member] | Level 1 [Member] | Equity instruments [Member] | Fixed income U.S. government sector fund [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Recurring [Member] | Level 1 [Member] | Equity instruments [Member] | Fixed income municipal sector fund [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities		0
Recurring [Member] | Level 1 [Member] | Equity instruments [Member] | Fixed income investement grade corporate sector fund [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Recurring [Member] | Level 1 [Member] | Equity instruments [Member] | Fixed income high-yield sector fund [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Recurring [Member] | Level 1 [Member] | Equity instruments [Member] | Fixed income real return sector fund [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Recurring [Member] | Level 1 [Member] | Equity instruments [Member] | Fixed income mortgage sector fund [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Recurring [Member] | Level 1 [Member] | Equity instruments [Member] | Fixed income asset-backed securities sector fund [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Recurring [Member] | Level 1 [Member] | Equity instruments [Member] | Fixed income emerging market sector fund [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Recurring [Member] | Level 1 [Member] | Equity instruments [Member] | Fixed income international sector fund [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Recurring [Member] | Level 1 [Member] | Equity instruments [Member] | Equity mutual fund - S&P 500 index [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	439	451
Recurring [Member] | Level 1 [Member] | Money market instruments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	3,518	2,591
Recurring [Member] | Level 1 [Member] | Certificates of deposit [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Recurring [Member] | Level 1 [Member] | Certificates of deposit [Member] | Debt instruments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0
Recurring [Member] | Level 1 [Member] | Certificates of deposit [Member] | Debt instruments [Member] | Commercial paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities		0
Recurring [Member] | Level 1 [Member] | Commercial paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Recurring [Member] | Level 1 [Member] | Commercial paper [Member] | Debt instruments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0
Recurring [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	1,945	2,288
Available-for-sale securities	4,276	4,187
Derivative assets	2,552	2,568
Embedded derivative assets	0	0
Total assets	8,773	9,043
Derivative liabilities	(1,037)	(1,071)
Embedded derivative liabilities	0	0
Total liabilities	(1,037)	(1,071)
Total net assets	7,736	7,972
Recurring [Member] | Level 2 [Member] | Foreign currency swaps [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	1,903	2,142
Derivative liabilities	(57)	(63)
Recurring [Member] | Level 2 [Member] | Interest rate cap [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities	0	0
Recurring [Member] | Level 2 [Member] | Interest rate swap [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	649	426
Derivative liabilities	(980)	(1,008)
Recurring [Member] | Level 2 [Member] | Debt instruments [Member] | U.S. government and agency obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	62	108
Recurring [Member] | Level 2 [Member] | Debt instruments [Member] | Municipal debt securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	19	20
Recurring [Member] | Level 2 [Member] | Debt instruments [Member] | Foreign government debt securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	3	3
Recurring [Member] | Level 2 [Member] | Debt instruments [Member] | Corporate debt securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	91	106
Recurring [Member] | Level 2 [Member] | Debt instruments [Member] | U.S. government agency mortgage-backed securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	100	105
Recurring [Member] | Level 2 [Member] | Debt instruments [Member] | Non-agency residential mortgage-backed securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	4
Recurring [Member] | Level 2 [Member] | Debt instruments [Member] | Non-agency commercial mortgage-backed securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	11
Recurring [Member] | Level 2 [Member] | Debt instruments [Member] | Asset-backed securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	12
Recurring [Member] | Level 2 [Member] | Equity instruments [Member] | Municipal debt securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	21
Recurring [Member] | Level 2 [Member] | Equity instruments [Member] | Fixed income short-term sector fund [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	40	40
Recurring [Member] | Level 2 [Member] | Equity instruments [Member] | Fixed income U.S. government sector fund [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	342	313
Recurring [Member] | Level 2 [Member] | Equity instruments [Member] | Fixed income municipal sector fund [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities		21
Recurring [Member] | Level 2 [Member] | Equity instruments [Member] | Fixed income investement grade corporate sector fund [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	299	298
Recurring [Member] | Level 2 [Member] | Equity instruments [Member] | Fixed income high-yield sector fund [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	37	37
Recurring [Member] | Level 2 [Member] | Equity instruments [Member] | Fixed income real return sector fund [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	287	231
Recurring [Member] | Level 2 [Member] | Equity instruments [Member] | Fixed income mortgage sector fund [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	637	639
Recurring [Member] | Level 2 [Member] | Equity instruments [Member] | Fixed income asset-backed securities sector fund [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	42	41
Recurring [Member] | Level 2 [Member] | Equity instruments [Member] | Fixed income emerging market sector fund [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	64	62
Recurring [Member] | Level 2 [Member] | Equity instruments [Member] | Fixed income international sector fund [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	164	162
Recurring [Member] | Level 2 [Member] | Equity instruments [Member] | Equity mutual fund - S&P 500 index [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Recurring [Member] | Level 2 [Member] | Money market instruments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	556	256
Recurring [Member] | Level 2 [Member] | Certificates of deposit [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	350	495
Recurring [Member] | Level 2 [Member] | Certificates of deposit [Member] | Debt instruments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	1,724
Recurring [Member] | Level 2 [Member] | Certificates of deposit [Member] | Debt instruments [Member] | Commercial paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities		1,341
Recurring [Member] | Level 2 [Member] | Commercial paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	1,039	1,537
Available-for-sale securities	344
Recurring [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Available-for-sale securities	48	21
Derivative assets	83	92
Embedded derivative assets	0	0
Total assets	131	113
Derivative liabilities	(13)	(10)
Embedded derivative liabilities	(27)	(24)
Total liabilities	(40)	(34)
Total net assets	91	79
Recurring [Member] | Level 3 [Member] | Foreign currency swaps [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	72	79
Derivative liabilities	(13)	(10)
Recurring [Member] | Level 3 [Member] | Interest rate cap [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities	0	0
Recurring [Member] | Level 3 [Member] | Interest rate swap [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	11	13
Derivative liabilities	0
Recurring [Member] | Level 3 [Member] | Debt instruments [Member] | U.S. government and agency obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Recurring [Member] | Level 3 [Member] | Debt instruments [Member] | Municipal debt securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Recurring [Member] | Level 3 [Member] | Debt instruments [Member] | Foreign government debt securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Recurring [Member] | Level 3 [Member] | Debt instruments [Member] | Corporate debt securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	4	1
Recurring [Member] | Level 3 [Member] | Debt instruments [Member] | U.S. government agency mortgage-backed securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Recurring [Member] | Level 3 [Member] | Debt instruments [Member] | Non-agency residential mortgage-backed securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	7	4
Recurring [Member] | Level 3 [Member] | Debt instruments [Member] | Non-agency commercial mortgage-backed securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	25	15
Recurring [Member] | Level 3 [Member] | Debt instruments [Member] | Asset-backed securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	12	1
Recurring [Member] | Level 3 [Member] | Equity instruments [Member] | Municipal debt securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0
Recurring [Member] | Level 3 [Member] | Equity instruments [Member] | Fixed income short-term sector fund [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Recurring [Member] | Level 3 [Member] | Equity instruments [Member] | Fixed income U.S. government sector fund [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Recurring [Member] | Level 3 [Member] | Equity instruments [Member] | Fixed income municipal sector fund [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities		0
Recurring [Member] | Level 3 [Member] | Equity instruments [Member] | Fixed income investement grade corporate sector fund [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Recurring [Member] | Level 3 [Member] | Equity instruments [Member] | Fixed income high-yield sector fund [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Recurring [Member] | Level 3 [Member] | Equity instruments [Member] | Fixed income real return sector fund [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Recurring [Member] | Level 3 [Member] | Equity instruments [Member] | Fixed income mortgage sector fund [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Recurring [Member] | Level 3 [Member] | Equity instruments [Member] | Fixed income asset-backed securities sector fund [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Recurring [Member] | Level 3 [Member] | Equity instruments [Member] | Fixed income emerging market sector fund [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Recurring [Member] | Level 3 [Member] | Equity instruments [Member] | Fixed income international sector fund [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Recurring [Member] | Level 3 [Member] | Equity instruments [Member] | Equity mutual fund - S&P 500 index [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Recurring [Member] | Level 3 [Member] | Money market instruments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents		0
Recurring [Member] | Level 3 [Member] | Certificates of deposit [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Recurring [Member] | Level 3 [Member] | Certificates of deposit [Member] | Debt instruments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0
Recurring [Member] | Level 3 [Member] | Certificates of deposit [Member] | Debt instruments [Member] | Commercial paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities		0
Recurring [Member] | Level 3 [Member] | Commercial paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Recurring [Member] | Level 3 [Member] | Commercial paper [Member] | Debt instruments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0
Recurring [Member] | Counterparty Netting & Collateral [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	(2,436)	(2,590)
Total assets	(2,436)	(2,590)
Derivative liabilities	1,027	1,038
Total liabilities	1,027	1,038
Total net assets	$ (1,409)	$ (1,552)