So that means no tell-all memoir, no blogging, and no Tweeting.
"If you know what is going on inside somebody's head all the time that's not a good place," the actress, 42, tells the December issue of British GQ.
"You can't read somebody's diary. You shouldn't read it. I burnt most of my journals after I remarried ... You're only going to find out bad things."
In the interview, however, Kidman gives a hint about the adventurousness that infused her romances over the years.
"My life has been about exploring types of love," she says. "I've explored obsession, I've explored loss and love in terms of being in a grief-stricken place, I've explored strange sexual fetish stuff, I've explored the mundane aspect of marriage, and monogamy. But I'm still on that journey."
And she's currently taking it with husband Keith Urban, whom she wed in June 2006. (Their daughter Sunday Rose is 15 months old.)
"[W]e're very together," she says, adding, "It's a very adventurous, extraordinary place to be: incredibly raw, incredibly dangerous and you're very much out at sea ... When you commit to someone like that you live and die together by that decision."
Being Mrs. CruiseWhile Kidman refuses to discuss her nearly 10-year marriage to Tom Cruise, she does reveal a few details about their relationship.
"I know my agents at the time were like, 'Do not get married! It will ruin your career!,' " says the actress, who was 23 when she wed the mega-star. "And I was like, 'But I'm in love!' All I know is that I wasn't someone interested in fame. And that's not why I got married."
As for why they split, she says people shouldn't look at their film Eyes Wide Shut (about a troubled couple), for clues. "[W]e were pretty happily married throughout that period," Kidman, who stars in the upcoming musical Nine alongside Kate Hudson, Penélope Cruz, and Fergie, tells GQ.
"People will always watch the movie in hindsight and go, 'Oh no, that must be where it all went wrong.' I don't want to say whether anything is or isn't true any more." ]