Consolidated Statement of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Deficit
BALANCE (in shares) at Dec. 31, 2015		117,232
BALANCE at Dec. 31, 2015	$ 1,462,748	$ 1,172	$ 1,762,394	$ (300,818)
Net income	46,307			46,307
Retirement of common stock (in shares)		(120)
Retirement of common stock	(3,528)	$ (1)	(3,527)
Dividends declared on common stock	(63,950)			(63,950)
Restricted stock compensation, net of forfeitures (in shares)		(1)
Restricted stock compensation, net of forfeitures	3,693		3,636	57
Income tax benefit of equity compensation	16		16
Stock option compensation expense, net of forfeitures	88		88
Restricted stock grants (in shares)		307
Restricted stock grants	3	$ 3
Stock options exercised (in shares)		59
Stock options exercised	1,079	$ 1	1,078
BALANCE (in shares) at Mar. 31, 2016		117,477
BALANCE at Mar. 31, 2016	1,446,456	$ 1,175	1,763,685	(318,404)
BALANCE (in shares) at Dec. 31, 2016		117,554
BALANCE at Dec. 31, 2016	1,458,963	$ 1,176	1,780,350	(322,563)
Net income	50,047			50,047
Retirement of common stock (in shares)		(153)
Retirement of common stock	(5,089)	$ (2)	(5,087)
Dividends declared on common stock	(50,036)			(50,036)
Restricted stock compensation, net of forfeitures	4,086		4,086
Restricted stock grants (in shares)		506
Restricted stock grants		$ 5	(5)
Stock options exercised (in shares)		233
Stock options exercised	5,190	$ 2	5,188
BALANCE (in shares) at Mar. 31, 2017		118,140
BALANCE at Mar. 31, 2017	$ 1,463,161	$ 1,181	$ 1,784,532	$ (322,552)