Fair Value Measurements - Roll Forward, Level 3 (Details) - Level 3 - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Rollforward for financial instruments measured at fair value using Level 3 inputs
Asset balance, beginning of period	$ 73,617	$ 79,137	$ 97,769	$ 78,166
Purchases/Additions	14,820	18,482	33,813	71,414
Sales/Reductions	(5,685)	(8,686)	(40,607)	(31,403)
Total gains or losses (realized or unrealized):
Included in Net Income	(3,441)	(2,605)	(11,664)	(31,849)
Asset balance, end of period	79,311	86,328	79,311	86,328
Trading securities.
Rollforward for financial instruments measured at fair value using Level 3 inputs
Asset balance, beginning of period		1		1
Total gains or losses (realized or unrealized):
Included in Net Income		(1)		(1)
Loans Held for Sale
Rollforward for financial instruments measured at fair value using Level 3 inputs
Asset balance, beginning of period	30,037	45,645	35,801	25,880
Purchases/Additions	8,881	8,066	25,384	51,105
Sales/Reductions	(5,685)	(8,686)	(23,108)	(23,817)
Total gains or losses (realized or unrealized):
Included in Net Income	(1,688)	(2,448)	(6,532)	(10,591)
Asset balance, end of period	31,545	42,577	31,545	42,577
MSR
Rollforward for financial instruments measured at fair value using Level 3 inputs
Asset balance, beginning of period	43,580	33,491	61,968	52,285
Purchases/Additions	5,939	10,416	8,429	20,309
Sales/Reductions			(17,499)	(7,586)
Total gains or losses (realized or unrealized):
Included in Net Income	(1,753)	(156)	(5,132)	(21,257)
Asset balance, end of period	$ 47,766	$ 43,751	$ 47,766	$ 43,751