Fair Value Measurements (Financial Assets and Liabilities Measured at Fair Value On a Recurring Basis) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013	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
Transfers from Level 1 to Level 2		27
Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	4,251	4,879
Available-for-sale securities	5,397	4,659
Derivative assets	58	70
Embedded derivative assets	0	0
Total assets	9,706	9,608
Derivative liabilities	(5)	(43)
Embedded derivative liabilities	(12)	(24)
Total liabilities	(17)	(67)
Total net assets	9,689	9,541
Recurring [Member] | Foreign currency swaps [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	1,139	2,221
Derivative liabilities	(131)	(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	580	439
Derivative liabilities	(766)	(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	104	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	16	20
Recurring [Member] | Debt instruments [Member] | Certificates Of Deposit [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	2,041	1,341
Recurring [Member] | Debt instruments [Member] | Commercial paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	495	633
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	128	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	87	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	5	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	51	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	13	13
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	43	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	312	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	22	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	327	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	42	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	293	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	648	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	47	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	66	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	170	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	484	451
Recurring [Member] | Money market instruments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	1,508	2,847
Recurring [Member] | Certificates of deposit [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	1,945	495
Recurring [Member] | Commercial paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	798	1,537
Recurring [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	900	2,591
Available-for-sale securities	526	451
Derivative assets	0	0
Embedded derivative assets	0	0
Total assets	1,426	3,042
Derivative liabilities	0	0
Embedded derivative liabilities	0	0
Total liabilities	0	0
Total net assets	1,426	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	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	42	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] | Certificates Of Deposit [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] | Commercial paper [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] | 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	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	484	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	900	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] | Commercial paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Recurring [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	3,351	2,288
Available-for-sale securities	4,798	4,187
Derivative assets	1,644	2,568
Embedded derivative assets	0	0
Total assets	9,793	9,043
Derivative liabilities	(889)	(1,071)
Embedded derivative liabilities	0	0
Total liabilities	(889)	(1,071)
Total net assets	8,904	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	1,076	2,142
Derivative liabilities	(123)	(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	568	426
Derivative liabilities	(766)	(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	16	20
Recurring [Member] | Level 2 [Member] | Debt instruments [Member] | Certificates Of Deposit [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	2,041	1,341
Recurring [Member] | Level 2 [Member] | Debt instruments [Member] | Commercial paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	495	633
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	124	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	87	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] | Fixed income short-term sector fund [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	43	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	312	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	22	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	327	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	42	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	293	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	648	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	47	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	66	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	170	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	608	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	1,945	495
Recurring [Member] | Level 2 [Member] | Commercial paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	798	1,537
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	73	21
Derivative assets	75	92
Embedded derivative assets	0	0
Total assets	148	113
Derivative liabilities	(8)	(10)
Embedded derivative liabilities	(12)	(24)
Total liabilities	(20)	(34)
Total net assets	128	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	63	79
Derivative liabilities	(8)	(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	12	13
Derivative liabilities	0	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] | Certificates Of Deposit [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] | Commercial paper [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	5	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	51	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	13	1
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	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	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] | Commercial paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Recurring [Member] | Counterparty Netting & Collateral [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	(1,661)	(2,590)
Total assets	(1,661)	(2,590)
Derivative liabilities	892	1,038
Total liabilities	892	1,038
Total net assets	$ (769)	$ (1,552)