Consolidated Statement of Comprehensive Income (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Statement of Partners' Capital [Abstract]
Net income	$ 1,066,246us-gaap_NetIncomeLoss	$ 1,138,480us-gaap_NetIncomeLoss	$ 1,029,498us-gaap_NetIncomeLoss
Other comprehensive income (loss), net of tax and reclassification adjustments:
Net unrealized gains (losses) on investment securities	93,275	(2,865)	114,825
Cash flow hedges adjustments	(96)		(112)
Foreign currency translation adjustment	(2,607)	381	519
Defined benefit plans liability adjustments	(207,407)	178,589	945
Total other comprehensive income (loss)	(116,835)	176,105	116,177
Total comprehensive income	$ 949,411	$ 1,314,585	$ 1,145,675

Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income. Excludes changes in equity resulting from investments by owners and distributions to owners.

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