Business Segments (Details 2) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Segment Reporting Information
Interest income	$ 302,669	$ 276,172
Charge for funds used	(120,414)	(88,280)
Interest spread on funds used	182,255	187,892
Interest expense	(30,547)	(23,968)
Credit on funds provided	120,414	88,280
Interest spread on funds provided	89,867	64,312
Net interest income before provision for credit losses	272,122	252,204
(Reversal of) provision for credit losses	7,068	1,440
Depreciation, amortization and (accretion), net	28,130	12,758
Segment pretax profit (loss)	228,004	144,671
Goodwill	469,433	469,433	$ 469,433
Segment assets	35,342,126	33,109,169	$ 34,788,840
Retail Banking
Segment Reporting Information
Interest income	81,648	77,371
Charge for funds used	(27,860)	(22,652)
Interest spread on funds used	53,788	54,719
Interest expense	(16,173)	(14,606)
Credit on funds provided	102,528	72,431
Interest spread on funds provided	86,355	57,825
Net interest income before provision for credit losses	140,143	112,544
(Reversal of) provision for credit losses	381	(1,582)
Depreciation, amortization and (accretion), net	2,344	43
Segment pretax profit (loss)	73,361	45,945
Goodwill	357,207	357,207
Segment assets	8,213,268	7,203,470
Commercial Banking
Segment Reporting Information
Interest income	191,796	177,082
Charge for funds used	(64,387)	(53,791)
Interest spread on funds used	127,409	123,291
Interest expense	(5,108)	(4,026)
Credit on funds provided	12,061	9,977
Interest spread on funds provided	6,953	5,951
Net interest income before provision for credit losses	134,362	129,242
(Reversal of) provision for credit losses	6,687	3,022
Depreciation, amortization and (accretion), net	(3,474)	(10,773)
Segment pretax profit (loss)	91,798	92,829
Goodwill	112,226	112,226
Segment assets	19,624,237	17,939,537
Other
Segment Reporting Information
Interest income	29,225	21,719
Charge for funds used	(28,167)	(11,837)
Interest spread on funds used	1,058	9,882
Interest expense	(9,266)	(5,336)
Credit on funds provided	5,825	5,872
Interest spread on funds provided	(3,441)	536
Net interest income before provision for credit losses	(2,383)	10,418
(Reversal of) provision for credit losses	0	0
Depreciation, amortization and (accretion), net	29,260	23,488
Segment pretax profit (loss)	62,845	5,897
Goodwill	0	0
Segment assets	$ 7,504,621	$ 7,966,162