Credit Facilities (Tables)

12 Months Ended

Dec. 31, 2016

Debt Disclosure [Abstract]

Outstanding Amount of Credit Facilities

Amounts outstanding under the Company’s credit facilities consist of the following:

	December 31
	2016		2015
	(In Thousands)
Unsecured revolving line of credit, $1,200,000,000, LIBOR plus 0.75% variable	$	325,000	$	125,000
Unsecured term notes:
November 30, 2011, Series D and E Senior Unsecured Notes, $250,000,000, 3.35% fixed, due November 30, 2016	—		250,000
July 29, 2016, Series G Senior Unsecured Notes, $50,000,000, 2.39% fixed, due July 29, 2021	50,000		—
December 2, 2013, Series F Senior Unsecured Notes, $250,000,000, 2.99% fixed, due December 2, 2023	250,000		250,000
November 30, 2016, Series H Senior Unsecured Notes, $250,000,000, 2.99% fixed, due November 30, 2026	250,000		—
Total debt	875,000		625,000
Less debt due within one year	325,000		375,000
Long-term debt, excluding current portion	$	550,000	$	250,000

Schedule of Maturities of Long-term Debt

Approximate maturities under the Company’s credit facilities are as follows (in thousands):

2017	$	325,000
2018	—
2019	—
2020	—
2021	50,000
Thereafter	500,000
	$	875,000