Consolidated Statements of Cash Flows - USD ($) $ in Thousands		9 Months Ended
		Sep. 30, 2017	Sep. 30, 2016
Cash flows from operating activities:
Net income		$ 171,998	$ 173,626
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for loan and lease losses		13,400	4,700
Depreciation, amortization and accretion, net		46,273	39,786
Deferred income taxes		(6,348)	(176)
Stock-based compensation		4,171	2,059
Gains on sale of bank properties		(2,667)
Other (gains) losses		(133)	14
Net gains on investment securities			(25,761)
Change in assets and liabilities:
Net increase in other assets (1)	[1]	(935)	(13,643)
Net decrease in other liabilities		(11,257)	(1,367)
Net cash provided by operating activities		214,502	179,238
Available-for-sale securities:
Proceeds from maturities and principal repayments		644,854	893,184
Proceeds from sales			533,687
Purchases		(864,049)	(2,673,977)
Other investments:
Proceeds from sales		13,318	17,636
Purchases		(11,484)	(17,959)
Loans:
Net increase in loans and leases resulting from originations and principal repayments		(626,262)	(676,234)
Proceeds from sales of loans originated for investment		1,775
Purchases of loans		(11,626)
Proceeds from bank-owned life insurance		4,226	5,777
Purchases of premises, equipment and software		(5,964)	(11,179)
Proceeds from sales of premises and equipment		3,857	63
Proceeds from sales of other real estate owned		635	407
Other		(1,572)	50
Net cash used in investing activities		(852,292)	(1,928,545)
Cash flows from financing activities
Net increase in deposits		800,951	903,603
Net decrease in short-term borrowings		(9,151)	(207,000)
Repayment of long-term debt		(10)	(10)
Dividends paid		(92,101)	(57,891)
Distributions paid			(363,624)
Stock tendered for payment of withholding taxes (1)	[1]	(120)	(146)
Proceeds from employee stock purchase plan		528
Net cash provided by (used in) financing activities		700,097	274,932
Net increase (decrease) in cash and cash equivalents		62,307	(1,474,375)
Cash and cash equivalents at beginning of period		1,052,058	2,650,195
Cash and cash equivalents at end of period		1,114,365	1,175,820
Supplemental disclosures
Interest paid		24,692	19,034
Income taxes paid, net of income tax refunds		87,240	152,950
Noncash investing and financing activities:
Transfers from loans and leases to other real estate owned		759	1,056
Transfers from loans and leases to loans held for sale		$ 1,759
Derivative liability entered into in connection with sale of investment securities			$ 8,828

[1] Prior period has been revised to conform to the current period presentation.