Consolidated Statement of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Statement Of Partners Capital [Abstract]
Net income	$ 381,053	$ 336,031	$ 729,980	$ 634,559
Other comprehensive income, net of tax and reclassification adjustments:
Net unrealized gains on investment securities	16,932	47,270	15,576	144,464
Cash flow hedges adjustments	(955)	(23)	(978)	(47)
Foreign currency translation adjustment	1,150	(1,565)	1,626	(1,618)
Defined benefit plans liability adjustments	4,359	3,486	8,331	7,807
Total other comprehensive income	21,486	49,168	24,555	150,606
Total comprehensive income	$ 402,539	$ 385,199	$ 754,535	$ 785,165