Condensed Consolidated Statements of Changes In Shareholders' Equity (Unaudited) (USD $) In Thousands, except Share data, unless otherwise specified		Total	Common Stock [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
BALANCE, VALUE at Dec. 31, 2013		$ 1,727,426	$ 1,514,485	$ 217,917	$ (4,976)
BALANCE, SHARES at Dec. 31, 2013			111,973,203
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect adjustment		(3,509)		(3,509)
Restated beginning balance		1,723,917		214,408
Net income		147,658		147,658
Other comprehensive income, net of tax		17,044			17,044
Stock issued in connection with merger, shares	[1]		104,385,087
Stock issued in connection with merger, value	[1]	1,989,030	1,989,030
Stock-based compensation		15,292	15,292
Stock repurchased and retired, shares			(403,828)
Stock repurchased and retired, value		(7,183)	(7,183)
Issuances of common stock under stock plans and related tax benefit, shares	[2]		4,206,658
Issuances of common stock under stock plans and related tax benefit, value	[2]	7,692	7,692
Cash dividends on common stock		(115,824)		(115,824)
BALANCE, VALUE at Dec. 31, 2014		3,777,626	3,519,316	246,242	12,068
BALANCE, SHARES at Dec. 31, 2014		220,161,120	220,161,120
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		47,129		47,129
Other comprehensive income, net of tax		7,573			7,573
Stock-based compensation		3,433	3,433
Stock repurchased and retired, shares			(130,818)
Stock repurchased and retired, value		(2,220)	(2,220)
Issuances of common stock under stock plans and related tax benefit, shares			423,427
Issuances of common stock under stock plans and related tax benefit, value		672	672
Cash dividends on common stock		(33,243)		(33,243)
BALANCE, VALUE at Mar. 31, 2015		$ 3,800,970	$ 3,521,201	$ 260,128	$ 19,641
BALANCE, SHARES at Mar. 31, 2015		220,453,729	220,453,729

[1] The amount of common stock issued in connection with the merger is net of $784,000 of issuance costs.

[2] The shares issued include 2,889,896 of warrants exercised.