Financial Statement Offsetting (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Derivative contracts, Assets
Gross Amounts	$ 3,066,577	$ 4,627,076
Netting in Consolidated Statements of Financial Condition	(2,873,083)	(4,255,998)
Net Amounts in Consolidated Statements of Financial Condition	193,494	371,078
Additional Amounts Available for Setoff	0	0
Available Collateral	0	0
Net Amount	193,494	371,078
Securities borrowing arrangements, Assets
Gross Amounts	7,900,395	7,743,562
Netting in Consolidated Statements of Financial Condition	0	0
Net Amounts in Consolidated Statements of Financial Condition	7,900,395	7,743,562
Additional Amounts Available for Setoff	(765,075)	(710,611)
Available Collateral	(1,291,875)	(647,290)
Net Amount	5,843,445	6,385,661
Reverse repurchase agreements, Assets
Gross Amounts	13,041,366	14,083,144
Netting in Consolidated Statements of Financial Condition	(8,695,905)	(10,220,656)
Net Amounts in Consolidated Statements of Financial Condition	4,345,461	3,862,488
Additional Amounts Available for Setoff	(587,698)	(176,275)
Available Collateral	(3,698,540)	(3,591,654)
Net Amount	59,223	94,559
Derivative contracts, Liabilities
Gross Amounts	3,324,730	4,880,022
Netting in Consolidated Statements of Financial Condition	(2,860,565)	(4,229,213)
Net Amounts in Consolidated Statements of Financial Condition	464,165	650,809
Additional Amounts Available for Setoff	0	0
Available Collateral	0	0
Net Amount	464,165	650,809
Securities lending arrangements, Liabilities
Gross Amounts	3,446,853	2,819,132
Netting in Consolidated Statements of Financial Condition	0	0
Net Amounts in Consolidated Statements of Financial Condition	3,446,853	2,819,132
Additional Amounts Available for Setoff	(765,075)	(710,611)
Available Collateral	(2,622,311)	(2,064,299)
Net Amount	59,467	44,222
Repurchase agreements, Liabilities
Gross Amounts	17,317,332	17,012,332
Netting in Consolidated Statements of Financial Condition	(8,695,905)	(10,220,656)
Net Amounts in Consolidated Statements of Financial Condition	8,621,427	6,791,676
Additional Amounts Available for Setoff	(587,698)	(176,275)
Available Collateral	(6,617,668)	(5,780,909)
Net Amount	1,416,061	834,492
Securities borrowing agreement, subject to review	5,793,700	6,337,500
Securities borrowing agreement, collateral received, subject to review	5,620,100	6,146,000
Repurchase agreement, net amount, subject to review	1,396,900	810,400
Repurchase agreements, collateral pledged, subject to review	$ 1,438,000	$ 834,200