Consolidated Statement of Stockholders' Equity (Unaudited) (USD $) In Thousands, unless otherwise specified	Total	Preferred Stock [Member]	Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Treasury Stock [Member]
Balance at Dec. 31, 2012	$ 1,402,069		$ 1,398	$ 1,376,601	$ 75,312	$ (46,224)	$ (5,018)
Net income	28,538				28,538
Change in other comprehensive income (loss), net of tax	(974)					(974)
Dividends declared:
Preferred stock
Common stock: $0.12/share	(16,927)				(16,927)
Issuance of common stock	(1,779)		8	155			(1,942)
Restricted stock compensation	1,083			1,083
Tax benefit of stock-based compensation	1,247			1,247
Balance at Mar. 31, 2013	1,413,257		1,406	1,379,086	86,923	(47,198)	(6,960)
Balance at Dec. 31, 2013	1,774,383	106,882	1,592	1,608,117	121,870	(56,924)	(7,154)
Net income	34,524				34,524
Change in other comprehensive income (loss), net of tax	12,883					12,883
Dividends declared:
Preferred stock	(2,322)				(2,322)
Common stock: $0.12/share	(20,016)				(20,016)
Issuance of common stock	2,347		12	5,939	(228)		(3,376)
Issuance of common stock - acquisitions	81,397		67	81,330
Restricted stock compensation	567			567
Tax benefit of stock-based compensation	1,224			1,224
Balance at Mar. 31, 2014	$ 1,884,987	$ 106,882	$ 1,671	$ 1,697,177	$ 133,828	$ (44,041)	$ (10,530)