Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Cash flows from operating activities:
Net income	$ 113,635	$ 120,391
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for loan and lease losses	8,900	2,600
Depreciation, amortization and accretion, net	30,220	24,495
Deferred income taxes	4,425	6,662
Stock-based compensation	2,994
Other gains	(133)	(25)
Net gains on sales of loans held for sale	(13)
Net gains on investment securities		(25,731)
Change in assets and liabilities:
Net decrease in other assets	13,487	14,157
Net decrease in other liabilities	(14,619)	(2,711)
Net cash provided by operating activities	158,896	139,838
Available-for-sale securities:
Proceeds from maturities and principal repayments	412,621	551,595
Proceeds from sales		534,107
Purchases	(438,348)	(1,554,942)
Other investments:
Proceeds from sales	11,463	11,801
Purchases	(9,651)	(11,832)
Loans:
Net increase in loans and leases resulting from originations and principal repayments	(539,237)	(466,843)
Proceeds from sales of loans originated for investment	672
Purchases of loans	(8,000)
Proceeds from bank-owned life insurance	3,987	1,021
Purchases of premises, equipment and software	(4,019)	(8,565)
Proceeds from sales of premises and equipment	27	50
Proceeds from sales of other real estate owned	635	167
Other	(1,046)	66
Net cash used in investing activities	(570,896)	(943,375)
Cash flows from financing activities
Net increase in deposits	657,730	60,180
Net decrease in short-term borrowings	(9,151)	(181,200)
Dividends paid	(61,400)	(30,000)
Distributions paid		(363,624)
Proceeds from employee stock purchase plan	528
Net cash provided by (used in) financing activities	587,707	(514,644)
Net increase (decrease) in cash and cash equivalents	175,707	(1,318,181)
Cash and cash equivalents at beginning of period	1,052,058	2,650,195
Cash and cash equivalents at end of period	1,227,765	1,332,014
Supplemental disclosures
Interest paid	15,154	12,663
Income taxes paid, net of income tax refunds	31,091	104,792
Noncash investing and financing activities:
Transfers from loans and leases to other real estate owned	524	202
Transfers from loans and leases to loans held for sale	$ 659
Derivative liability entered into in connection with sale of investment securities		$ 8,828