Organization (Details Textual) $ in Thousands		3 Months Ended
		Mar. 31, 2019 USD ($) acquisition bank_branch	Mar. 31, 2018 USD ($)
Business Acquisition [Line Items]
Number of Businesses Acquired | acquisition		29
Cumulative effect of change in accounting principle | $	[1]	$ 938	$ 0
CALIFORNIA
Business Acquisition [Line Items]
Retail Branch Locations		74
NORTH CAROLINA
Business Acquisition [Line Items]
Retail Branch Locations		1

[1] Three Months Ended March 31, 2018 Common Stock Accumulated Additional Other Par Paid-in Retained Treasury Comprehensive Shares Value Capital Earnings Stock Income (Loss) Total (Unaudited) (Dollars in thousands)Balance, December 31, 2017128,782,878 $1,305 $4,287,487 $723,471 $(65,836) $31,171 $4,977,598Cumulative effect of changes in accounting principles (2)— — — (6,136) — 6,136 —Net earnings— — — 118,276 — — 118,276Other comprehensive loss - net unrealized loss on securities available-for-sale, net of tax— — — — — (49,243) (49,243)Restricted stock awarded and earned stock compensation, net of shares forfeited96,034 1 7,198 — — — 7,199Restricted stock surrendered(55,186) — — — (2,858) — (2,858)Common stock repurchased under Stock Repurchase Program(2,285,855) (23) (119,770) — — — (119,793)Cash dividends paid: Common stock, $0.50/share— — (63,689) — — — (63,689)Balance, March 31, 2018126,537,871 $1,283 $4,111,226 $835,611 $(68,694) $(11,936) $4,867,490